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MERGERS AND ACQUISITIONS - Schedule of Estimated Acquisition-date Fair Values of the Assets Acquired and Liabilities Assumed (Details) - USD ($) $ in Thousands	Mar. 01, 2025	Feb. 28, 2025	Apr. 01, 2024	Sep. 30, 2025	Dec. 31, 2024
Consideration paid
Goodwill				$ 383,323	$ 333,695
CrossFirst
Assets acquired
Cash and cash equivalents	$ 385,808
Securities	725,622
Portfolio loans, net of ACL	6,023,063
Premises and equipment	69,673
Other intangible assets	81,783
Other assets	212,832
Total assets acquired	7,498,781
Liabilities assumed
Deposits	6,571,699
Short-term borrowings	11,148
Long-term borrowings	68,922
Subordinated notes, net of unamortized issuance costs	0
Junior subordinated debt owed to unconsolidated trusts	2,238
Other liabilities	85,347
Total liabilities assumed	6,739,354
Net assets acquired	759,427
Consideration paid
Cash	4
Total consideration paid	808,980	$ 6,000
Goodwill	49,553
CrossFirst \| Common stock
Consideration paid
Common stock, Preferred stock and Replacement awards	795,227
CrossFirst \| Preferred stock
Consideration paid
Common stock, Preferred stock and Replacement awards	7,750
CrossFirst \| Replacement awards
Consideration paid
Common stock, Preferred stock and Replacement awards	$ 5,999
M&M
Assets acquired
Cash and cash equivalents			$ 33,577
Securities			8,086
Portfolio loans, net of ACL			417,230
Premises and equipment			2,045
Other intangible assets			6,346
Other assets			10,461
Total assets acquired			477,745
Liabilities assumed
Deposits			392,838
Short-term borrowings			35,932
Long-term borrowings			1,450
Subordinated notes, net of unamortized issuance costs			3,911
Junior subordinated debt owed to unconsolidated trusts			2,594
Other liabilities			7,342
Total liabilities assumed			444,067
Net assets acquired			33,678
Consideration paid
Cash			15,200
Total consideration paid			49,575
Goodwill			15,897
M&M \| Common stock
Consideration paid
Common stock, Preferred stock and Replacement awards			34,375
M&M \| Preferred stock
Consideration paid
Common stock, Preferred stock and Replacement awards			0
M&M \| Replacement awards
Consideration paid
Common stock, Preferred stock and Replacement awards			$ 0

REGULATORY CAPITAL

9 Months Ended

Sep. 30, 2025

Banking and Thrift, Other Disclosure [Abstract]

REGULATORY CAPITAL

NOTE 8. REGULATORY CAPITAL

First Busey and its subsidiary bank are subject to various regulatory capital requirements administered by federal banking agencies. Failure to meet minimum capital requirements can initiate certain mandatory—and possibly additional discretionary—actions by regulators that, if undertaken, could have a direct material effect on First Busey's consolidated financial statements. Capital amounts and classification also are subject to qualitative judgments by regulators about components, risk weightings, and other factors.

Banking regulations identify five capital categories for insured depository institutions: well capitalized, adequately capitalized, undercapitalized, significantly undercapitalized, and critically undercapitalized. As of September 30, 2025 and 2024, all capital ratios of First Busey and its subsidiary bank exceeded well capitalized levels under the applicable regulatory capital adequacy guidelines. Management believes that no events or changes have occurred subsequent to September 30, 2025, that would change this designation.

Capital Amounts and Ratios

The following tables summarize regulatory capital requirements applicable to First Busey and its subsidiary bank:


	As of September 30, 2025
	Actual				Minimum Capital Requirement				Minimum To Be Well Capitalized
(dollars in thousands)	Amount		Ratio		Amount		Ratio		Amount		Ratio
Common equity Tier 1 capital to risk weighted assets
First Busey	$	1,907,982	12.33	%	$	696,419	4.50	%	$	1,005,938	6.50	%
Busey Bank	$	2,118,059	13.73	%	$	694,126	4.50	%	$	1,002,626	6.50	%

Tier 1 capital to risk weighted assets
First Busey	$	2,130,732	13.77	%	$	928,558	6.00	%	$	1,238,078	8.00	%
Busey Bank	$	2,118,059	13.73	%	$	925,501	6.00	%	$	1,234,002	8.00	%

Total capital to risk weighted assets
First Busey	$	2,458,553	15.89	%	$	1,238,078	8.00	%	$	1,547,597	10.00	%
Busey Bank	$	2,262,302	14.67	%	$	1,234,002	8.00	%	$	1,542,502	10.00	%

Leverage ratio of Tier 1 capital to average assets
First Busey	$	2,130,732	11.62	%	$	733,327	4.00	%	N/A		N/A
Busey Bank	$	2,118,059	11.59	%	$	731,219	4.00	%	$	914,024	5.00	%


	As of December 31, 2024
	Actual				Minimum Capital Requirement				Minimum To Be Well Capitalized
(dollars in thousands)	Amount		Ratio		Amount		Ratio		Amount		Ratio
Common equity Tier 1 capital to risk weighted assets
First Busey	$	1,237,301	14.10	%	$	394,840	4.50	%	$	570,325	6.50	%
Busey Bank	$	1,438,296	16.46	%	$	393,277	4.50	%	$	568,067	6.50	%

Tier 1 capital to risk weighted assets
First Busey	$	1,314,301	14.98	%	$	526,453	6.00	%	$	701,938	8.00	%
Busey Bank	$	1,438,296	16.46	%	$	524,369	6.00	%	$	699,159	8.00	%

Total capital to risk weighted assets
First Busey	$	1,625,943	18.53	%	$	701,938	8.00	%	$	877,422	10.00	%
Busey Bank	$	1,520,938	17.40	%	$	699,159	8.00	%	$	873,949	10.00	%

Leverage ratio of Tier 1 capital to average assets
First Busey	$	1,314,301	11.06	%	$	475,348	4.00	%	N/A		N/A
Busey Bank	$	1,438,296	12.14	%	$	473,878	4.00	%	$	592,347	5.00	%

Capital Conservation Buffer

In July 2013, U.S. federal banking authorities approved the Basel III Rule for strengthening international capital standards. The Basel III Rule introduced a capital conservation buffer, composed entirely of common equity Tier 1 capital, which is added to the minimum risk-weighted asset ratios. The capital conservation buffer is not a minimum capital requirement; however, banking institutions with a ratio of common equity Tier 1 capital to risk-weighted assets below the capital conservation buffer will face constraints on dividends, equity repurchases, and discretionary bonus payments based on the amount of the shortfall. In order to refrain from restrictions on dividends, equity repurchases, and discretionary bonus payments, banking institutions must maintain minimum ratios of (1) common equity Tier 1 capital to risk-weighted assets of at least 7.0%, which First Busey exceeded by 533 bps as of September 30, 2025, (2) Tier 1 capital to risk-weighted assets of at least 8.5%, which First Busey exceeded by 527 bps as of September 30, 2025, and (3) total capital to risk-weighted assets of at least 10.5%, which First Busey exceeded by 539 bps as of September 30, 2025.

- Definition

The entire disclosure for regulatory capital requirement for depository and lending institutions. Institutions include, but not are not limited to, finance company, insured depository institution, bank holding company, savings and loan association holding company, bank and savings institution not federally insured, mortgage company, foreign financial institution and credit union.

+ References + Details

CONSOLIDATED BALANCE SHEETS (Unaudited) - USD ($) $ in Thousands	Sep. 30, 2025	Dec. 31, 2024
Cash and cash equivalents:
Cash and due from banks	$ 193,273	$ 129,444
Interest-bearing deposits	192,201	568,215
Total cash and cash equivalents	385,474	697,659
Debt securities available for sale	2,099,259	1,810,221
Debt securities held to maturity	784,821	826,630
Equity securities	15,931	15,862
Loans held for sale	8,943	3,657
Portfolio loans (net of ACL of $174,181 at September 30, 2025, and $83,404 at December 31, 2024)	13,424,085	7,613,683
Restricted bank stock	77,006	49,930
Premises and equipment, net	190,721	118,820
Goodwill	383,323	333,695
Other intangible assets, net	101,880	32,280
Cash surrender value of bank owned life insurance	258,771	185,087
Other assets	458,414	359,198
Total assets	18,188,628	12,046,722
Deposits:
Noninterest-bearing	3,554,936	2,719,907
Interest-bearing	11,515,226	7,262,583
Total deposits	15,070,162	9,982,490
Securities sold under agreements to repurchase	147,152	155,610
Long-term borrowings	92,431	0
Subordinated notes, net of unamortized issuance costs	103,283	227,723
Junior subordinated debt owed to unconsolidated trusts	77,257	74,815
Other liabilities	249,508	222,815
Total liabilities	15,739,793	10,663,453
Outstanding commitments and contingent liabilities (see Notes 5 and 11)
Stockholders’ equity
Preferred stock, $0.001 par value, liquidation preference $222,750 at September 30, 2025 and zero at December 31, 2024	0	0
Common stock, $0.001 par value	93	60
Additional paid-in capital	2,373,500	1,360,530
Retained earnings	303,077	294,054
AOCI	(136,801)	(207,039)
Total stockholders’ equity before treasury stock	2,539,869	1,447,605
Treasury stock at cost	(91,034)	(64,336)
Total stockholders’ equity	2,448,835	1,383,269
Total liabilities and stockholders’ equity	$ 18,188,628	$ 12,046,722
Preferred shares outstanding (in shares)	222,750	0
Preferred shares issued (in shares)	222,750	0
Common shares issued (in shares)	92,694,541	59,546,273
Less: Treasury (in shares)	3,905,498	2,650,292
Common stock outstanding (in shares)	88,789,043	56,895,981

REGULATORY CAPITAL - Schedule of Regulatory Capital Requirements Applicable to Busey and Busey Bank (Details) $ in Thousands	Sep. 30, 2025 USD ($)	Dec. 31, 2024 USD ($)
Common Equity Tier 1 Capital to Risk Weighted Assets, Amount
Actual	$ 1,907,982	$ 1,237,301
Minimum Capital Requirement	696,419	394,840
Minimum To Be Well Capitalized	$ 1,005,938	$ 570,325
Common Equity Tier 1 Capital to Risk Weighted Assets, Ratio
Actual	0.1233	0.1410
Minimum Capital Requirement	0.0450	0.0450
Minimum To Be Well Capitalized	0.0650	0.0650
Tier 1 Capital to Risk Weighted Assets, Amount
Actual	$ 2,130,732	$ 1,314,301
Minimum Capital Requirement	928,558	526,453
Minimum To Be Well Capitalized	$ 1,238,078	$ 701,938
Tier 1 Capital to Risk Weighted Assets, Ratio
Actual	0.1377	0.1498
Minimum Capital Requirement	0.0600	0.0600
Minimum To Be Well Capitalized	0.0800	0.0800
Total Capital to Risk Weighted Assets, Amount
Actual	$ 2,458,553	$ 1,625,943
Minimum Capital Requirement	1,238,078	701,938
Minimum To Be Well Capitalized	$ 1,547,597	$ 877,422
Total Capital to Risk Weighted Assets, Ratio
Actual	0.1589	0.1853
Minimum Capital Requirement	0.0800	0.0800
Minimum To Be Well Capitalized	0.1000	0.1000
Leverage Ratio of Tier 1 Capital to Average Assets, Amount
Actual	$ 2,130,732	$ 1,314,301
Minimum Capital Requirement	$ 733,327	$ 475,348
Leverage Ratio of Tier 1 Capital to Average Assets, Ratio
Actual	0.1162	0.1106
Minimum Capital Requirement	0.0400	0.0400
Busey Bank
Common Equity Tier 1 Capital to Risk Weighted Assets, Amount
Actual	$ 2,118,059	$ 1,438,296
Minimum Capital Requirement	694,126	393,277
Minimum To Be Well Capitalized	$ 1,002,626	$ 568,067
Common Equity Tier 1 Capital to Risk Weighted Assets, Ratio
Actual	0.1373	0.1646
Minimum Capital Requirement	0.0450	0.0450
Minimum To Be Well Capitalized	0.0650	0.0650
Tier 1 Capital to Risk Weighted Assets, Amount
Actual	$ 2,118,059	$ 1,438,296
Minimum Capital Requirement	925,501	524,369
Minimum To Be Well Capitalized	$ 1,234,002	$ 699,159
Tier 1 Capital to Risk Weighted Assets, Ratio
Actual	0.1373	0.1646
Minimum Capital Requirement	0.0600	0.0600
Minimum To Be Well Capitalized	0.0800	0.0800
Total Capital to Risk Weighted Assets, Amount
Actual	$ 2,262,302	$ 1,520,938
Minimum Capital Requirement	1,234,002	699,159
Minimum To Be Well Capitalized	$ 1,542,502	$ 873,949
Total Capital to Risk Weighted Assets, Ratio
Actual	0.1467	0.1740
Minimum Capital Requirement	0.0800	0.0800
Minimum To Be Well Capitalized	0.1000	0.1000
Leverage Ratio of Tier 1 Capital to Average Assets, Amount
Actual	$ 2,118,059	$ 1,438,296
Minimum Capital Requirement	731,219	473,878
Minimum To Be Well Capitalized	$ 914,024	$ 592,347
Leverage Ratio of Tier 1 Capital to Average Assets, Ratio
Actual	0.1159	0.1214
Minimum Capital Requirement	0.0400	0.0400
Minimum To Be Well Capitalized	0.0500	0.0500

DERIVATIVE FINANCIAL INSTRUMENTS - Schedule of the Interest-Rate Swaps Designated as Cash Flow Hedges (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2025	Sep. 30, 2024	Sep. 30, 2025	Sep. 30, 2024	Dec. 31, 2024
Interest Rate Swap
Balances carried in AOCI
Unrealized gains (losses) on cash flow hedges, net of tax	$ 0	$ 0	$ 0	$ 0
Cash Flow Hedging \| Interest Rate Swap
Balances carried in AOCI
Unrealized gains (losses) on cash flow hedges, net of tax			(8,010)		$ (19,805)
Cash Flow Hedging \| Interest Rate Swap \| Other assets
Gross aggregate fair value of the swaps
Gross aggregate fair value of swap assets	3,617		3,617		0
Cash Flow Hedging \| Interest Rate Swap \| Other liabilities
Gross aggregate fair value of the swaps
Gross aggregate fair value of swap liabilities	15,670		15,670		27,770
Cash Flow Hedging \| Prime Loan Swap
Derivative [Line Items]
Notional amount	$ 300,000		$ 300,000		$ 300,000
Weighted average rate: receive-fixed	4.81%		4.81%		4.81%
Weighted average variable interest rates	7.37%		7.37%		7.62%
Weighted average maturity			3 years 4 months 6 days		4 years 1 month 6 days
Cash Flow Hedging \| SOFR Loan Swap
Derivative [Line Items]
Notional amount	$ 200,000		$ 200,000		$ 200,000
Weighted average rate: receive-fixed	3.78%		3.78%		3.78%
Weighted average variable interest rates	4.25%		4.25%		0.00%
Weighted average maturity			4 years 3 days		4 years 9 months 3 days

BORROWINGS - Short-term Borrowings (Details) - USD ($)	9 Months Ended
BORROWINGS - Short-term Borrowings (Details) - USD ($)	Sep. 30, 2025	Dec. 31, 2024
Short-Term Debt [Line Items]
Short-term debt	$ 0	$ 0
Minimum
Short-Term Debt [Line Items]
Short-term borrowings, mature period	1 day
Maximum
Short-Term Debt [Line Items]
Short-term borrowings, mature period	90 days

BORROWINGS - Revolving Line of Credit (Details) - Revolving Credit Facility - USD ($)	May 28, 2021	Sep. 30, 2025
Short-Term Debt [Line Items]
Issuance of debt	$ 40,000,000
Floating interest rate margin (as a percent)	1.80%
Balance outstanding		$ 0

FAIR VALUE MEASUREMENTS - Schedule of Estimated Fair Values of Financial Instruments (Details) - USD ($) $ in Thousands	Sep. 30, 2025	Dec. 31, 2024
Financial assets
Debt securities held to maturity	$ 659,471	$ 675,053
Restricted bank stock	77,006	49,930
Portfolio loans, net	13,424,085	7,613,683
Financial liabilities
Junior subordinated debt owed to unconsolidated trusts	77,257	74,815
Level 1 Inputs \| Carrying Amount
Financial assets
Cash and cash equivalents	385,474	697,659
Level 1 Inputs \| Fair Value
Financial assets
Cash and cash equivalents	385,474	697,659
Level 2 Inputs \| Carrying Amount
Financial assets
Debt securities held to maturity	784,821	826,630
Loans held for sale	8,943	3,657
Restricted bank stock	77,006	49,930
Accrued interest receivable	79,578	45,141
Financial liabilities
Time deposits	2,433,788	1,490,635
Securities sold under agreements to repurchase	147,152	155,610
Long-term borrowings	92,431	0
Junior subordinated debt owed to unconsolidated trusts	77,257	74,815
Accrued interest payable	24,355	21,129
Level 2 Inputs \| Fair Value
Financial assets
Debt securities held to maturity	659,471	675,053
Loans held for sale	8,993	3,726
Restricted bank stock	77,006	49,930
Accrued interest receivable	79,578	45,141
Financial liabilities
Time deposits	2,428,428	1,481,591
Securities sold under agreements to repurchase	147,152	155,610
Long-term borrowings	92,452	0
Junior subordinated debt owed to unconsolidated trusts	71,478	67,314
Accrued interest payable	24,355	21,129
Level 3 Inputs \| Carrying Amount
Financial assets
Portfolio loans, net	13,424,085	7,613,683
Mortgage servicing rights	1,441	1,304
Other servicing rights	2,274	1,482
Level 3 Inputs \| Fair Value
Financial assets
Portfolio loans, net	13,505,193	7,426,158
Mortgage servicing rights	5,260	5,627
Other servicing rights	2,315	1,591
Level 3 Inputs \| Subordinated Debt \| Carrying Amount
Financial liabilities
Long-term borrowings	103,283	227,723
Level 3 Inputs \| Subordinated Debt \| Fair Value
Financial liabilities
Long-term borrowings	$ 98,490	$ 219,043

DEBT SECURITIES - Schedule of Amortized Cost, Unrealized or Unrecognized Gains and Losses, and Fair Values of Securities Classified as AFS and HTM (Details) - USD ($) $ in Thousands	Sep. 30, 2025	Dec. 31, 2024
Debt securities available for sale
Amortized Cost	$ 2,251,731	$ 2,039,952
Gross unrealized gains	9,753	594
Gross unrealized losses	(162,225)	(230,325)
Fair Value	2,099,259	1,810,221
Debt securities held to maturity
Amortized Cost	784,821	826,630
Gross unrecognized gains	0	0
Gross unrecognized losses	(125,350)	(151,577)
Fair Value	659,471	675,053
Obligations of U.S. government corporations and agencies
Debt securities available for sale
Amortized Cost	113,676	1,408
Gross unrealized gains	124	0
Gross unrealized losses	(195)	(8)
Fair Value	113,605	1,400
Obligations of states and political subdivisions
Debt securities available for sale
Amortized Cost	259,470	156,534
Gross unrealized gains	655	31
Gross unrealized losses	(12,581)	(16,736)
Fair Value	247,544	139,829
Asset-backed securities
Debt securities available for sale
Amortized Cost	285,052	336,379
Gross unrealized gains	510	181
Gross unrealized losses	0	(3)
Fair Value	285,562	336,557
Commercial mortgage-backed securities
Debt securities available for sale
Amortized Cost	147,183	107,305
Gross unrealized gains	541	0
Gross unrealized losses	(11,743)	(15,131)
Fair Value	135,981	92,174
Debt securities held to maturity
Amortized Cost	398,375	415,530
Gross unrecognized gains	0	0
Gross unrecognized losses	(68,743)	(77,242)
Fair Value	329,632	338,288
Residential mortgage-backed securities
Debt securities available for sale
Amortized Cost	1,395,849	1,279,090
Gross unrealized gains	7,513	19
Gross unrealized losses	(135,786)	(191,899)
Fair Value	1,267,576	1,087,210
Debt securities held to maturity
Amortized Cost	386,446	411,100
Gross unrecognized gains	0	0
Gross unrecognized losses	(56,607)	(74,335)
Fair Value	329,839	336,765
Corporate debt securities
Debt securities available for sale
Amortized Cost	50,501	159,236
Gross unrealized gains	410	363
Gross unrealized losses	(1,920)	(6,548)
Fair Value	$ 48,991	$ 153,051

CONSOLIDATED BALANCE SHEETS (Unaudited) (Parenthetical) - USD ($) $ in Thousands	Sep. 30, 2025	Dec. 31, 2024
Statement of Financial Position [Abstract]
Portfolio loans, allowance for credit losses	$ 174,181	$ 83,404
Preferred stock, par value (in dollars per share)	$ 0.001	$ 0.001
Preferred stock, liquidation preference	$ 222,750
Common stock, par value (in dollars per share)	$ 0.001	$ 0.001
Preferred stock, shares authorized (in shares)	1,000,000	1,000,000
Common stock, shares authorized (in shares)	200,000,000	100,000,000

PORTFOLIO LOANS - Schedule of Risk Grades Segregated by Category and Class of Portfolio Loans (Details) - USD ($) $ in Thousands	Sep. 30, 2025	Dec. 31, 2024
Financing Receivable, Credit Quality Indicator [Line Items]
Total portfolio loans	$ 13,598,266	$ 7,697,087
Pass
Financing Receivable, Credit Quality Indicator [Line Items]
Total portfolio loans	11,824,501	6,764,070
Watch
Financing Receivable, Credit Quality Indicator [Line Items]
Total portfolio loans	1,291,575	756,610
Special Mention
Financing Receivable, Credit Quality Indicator [Line Items]
Total portfolio loans	332,765	92,296
Substandard
Financing Receivable, Credit Quality Indicator [Line Items]
Total portfolio loans	103,329	62,023
Substandard Non-accrual
Financing Receivable, Credit Quality Indicator [Line Items]
Total portfolio loans	46,096	22,088
Commercial loans
Financing Receivable, Credit Quality Indicator [Line Items]
Total portfolio loans	10,919,490	5,552,288
Commercial loans \| Pass
Financing Receivable, Credit Quality Indicator [Line Items]
Total portfolio loans	9,172,355	4,635,264
Commercial loans \| Watch
Financing Receivable, Credit Quality Indicator [Line Items]
Total portfolio loans	1,284,255	747,202
Commercial loans \| Special Mention
Financing Receivable, Credit Quality Indicator [Line Items]
Total portfolio loans	325,157	91,414
Commercial loans \| Substandard
Financing Receivable, Credit Quality Indicator [Line Items]
Total portfolio loans	100,564	59,480
Commercial loans \| Substandard Non-accrual
Financing Receivable, Credit Quality Indicator [Line Items]
Total portfolio loans	37,159	18,928
Commercial loans \| C&I and other commercial
Financing Receivable, Credit Quality Indicator [Line Items]
Total portfolio loans	4,395,871	1,904,515
Commercial loans \| C&I and other commercial \| Pass
Financing Receivable, Credit Quality Indicator [Line Items]
Total portfolio loans	3,707,153	1,545,338
Commercial loans \| C&I and other commercial \| Watch
Financing Receivable, Credit Quality Indicator [Line Items]
Total portfolio loans	433,278	281,424
Commercial loans \| C&I and other commercial \| Special Mention
Financing Receivable, Credit Quality Indicator [Line Items]
Total portfolio loans	152,267	36,152
Commercial loans \| C&I and other commercial \| Substandard
Financing Receivable, Credit Quality Indicator [Line Items]
Total portfolio loans	74,109	37,749
Commercial loans \| C&I and other commercial \| Substandard Non-accrual
Financing Receivable, Credit Quality Indicator [Line Items]
Total portfolio loans	29,064	3,852
Commercial loans \| CRE
Financing Receivable, Credit Quality Indicator [Line Items]
Total portfolio loans	5,424,095	3,269,564
Commercial loans \| CRE \| Pass
Financing Receivable, Credit Quality Indicator [Line Items]
Total portfolio loans	4,453,517	2,744,018
Commercial loans \| CRE \| Watch
Financing Receivable, Credit Quality Indicator [Line Items]
Total portfolio loans	794,313	438,945
Commercial loans \| CRE \| Special Mention
Financing Receivable, Credit Quality Indicator [Line Items]
Total portfolio loans	147,237	55,041
Commercial loans \| CRE \| Substandard
Financing Receivable, Credit Quality Indicator [Line Items]
Total portfolio loans	21,228	16,507
Commercial loans \| CRE \| Substandard Non-accrual
Financing Receivable, Credit Quality Indicator [Line Items]
Total portfolio loans	7,800	15,053
Commercial loans \| Real estate construction
Financing Receivable, Credit Quality Indicator [Line Items]
Total portfolio loans	1,099,524	378,209
Commercial loans \| Real estate construction \| Pass
Financing Receivable, Credit Quality Indicator [Line Items]
Total portfolio loans	1,011,685	345,908
Commercial loans \| Real estate construction \| Watch
Financing Receivable, Credit Quality Indicator [Line Items]
Total portfolio loans	56,664	26,833
Commercial loans \| Real estate construction \| Special Mention
Financing Receivable, Credit Quality Indicator [Line Items]
Total portfolio loans	25,653	221
Commercial loans \| Real estate construction \| Substandard
Financing Receivable, Credit Quality Indicator [Line Items]
Total portfolio loans	5,227	5,224
Commercial loans \| Real estate construction \| Substandard Non-accrual
Financing Receivable, Credit Quality Indicator [Line Items]
Total portfolio loans	295	23
Retail loans
Financing Receivable, Credit Quality Indicator [Line Items]
Total portfolio loans	2,678,776	2,144,799
Retail loans \| Pass
Financing Receivable, Credit Quality Indicator [Line Items]
Total portfolio loans	2,652,146	2,128,806
Retail loans \| Watch
Financing Receivable, Credit Quality Indicator [Line Items]
Total portfolio loans	7,320	9,408
Retail loans \| Special Mention
Financing Receivable, Credit Quality Indicator [Line Items]
Total portfolio loans	7,608	882
Retail loans \| Substandard
Financing Receivable, Credit Quality Indicator [Line Items]
Total portfolio loans	2,765	2,543
Retail loans \| Substandard Non-accrual
Financing Receivable, Credit Quality Indicator [Line Items]
Total portfolio loans	8,937	3,160
Retail loans \| CRE
Financing Receivable, Credit Quality Indicator [Line Items]
Total portfolio loans	2,196,246	1,696,457
Retail loans \| CRE \| Pass
Financing Receivable, Credit Quality Indicator [Line Items]
Total portfolio loans	2,170,254	1,680,640
Retail loans \| CRE \| Watch
Financing Receivable, Credit Quality Indicator [Line Items]
Total portfolio loans	7,320	9,408
Retail loans \| CRE \| Special Mention
Financing Receivable, Credit Quality Indicator [Line Items]
Total portfolio loans	7,608	882
Retail loans \| CRE \| Substandard
Financing Receivable, Credit Quality Indicator [Line Items]
Total portfolio loans	2,759	2,543
Retail loans \| CRE \| Substandard Non-accrual
Financing Receivable, Credit Quality Indicator [Line Items]
Total portfolio loans	8,305	2,984
Retail loans \| Retail other
Financing Receivable, Credit Quality Indicator [Line Items]
Total portfolio loans	482,530	448,342
Retail loans \| Retail other \| Pass
Financing Receivable, Credit Quality Indicator [Line Items]
Total portfolio loans	481,892	448,166
Retail loans \| Retail other \| Watch
Financing Receivable, Credit Quality Indicator [Line Items]
Total portfolio loans	0	0
Retail loans \| Retail other \| Special Mention
Financing Receivable, Credit Quality Indicator [Line Items]
Total portfolio loans	0	0
Retail loans \| Retail other \| Substandard
Financing Receivable, Credit Quality Indicator [Line Items]
Total portfolio loans	6	0
Retail loans \| Retail other \| Substandard Non-accrual
Financing Receivable, Credit Quality Indicator [Line Items]
Total portfolio loans	$ 632	$ 176

STOCK-BASED COMPENSATION - RSU, PSU, and DSU Narrative (Details) - USD ($) $ in Millions					9 Months Ended
	Jul. 23, 2025	May 29, 2025	Mar. 26, 2025	Mar. 01, 2025	Sep. 30, 2025
RSU Awards
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Number of shares of common stock per award (in shares)					1
Granted (in shares)					366,487
RSU Awards \| Management \| 2020 Equity Plan
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Granted (in shares)	13,724	4,494	348,269
Grant date fair value of the award	$ 0.3	$ 0.1	$ 7.7
Vesting period		3 years	3 years
RSU Awards \| Management \| 2020 Equity Plan \| Minimum
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Requisite service periods			1 year
PSU Awards
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Number of shares of common stock per award (in shares)					1
Granted (in shares)					407,723
Market Based Performance Stock Units \| 2020 Equity Plan
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Granted (in shares)			174,126	59,471
Grant date fair value of the award			$ 3.4	$ 1.3
Market Based Performance Stock Units \| 2020 Equity Plan \| Minimum
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Vesting percentage			0.00%	0.00%
Market Based Performance Stock Units \| 2020 Equity Plan \| Maximum
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Granted (in shares)			278,602	95,154
Vesting percentage			160.00%	160.00%
Performance Based Performance Stock Units \| 2020 Equity Plan
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Granted (in shares)			174,126
Grant date fair value of the award			$ 3.9
Performance Based Performance Stock Units \| 2020 Equity Plan \| Minimum
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Vesting percentage			0.00%
Performance Based Performance Stock Units \| 2020 Equity Plan \| Maximum
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Granted (in shares)			278,602
Vesting percentage			160.00%
DSU Awards
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Granted (in shares)					39,846
DSU Awards \| Management
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Number of shares of common stock per award (in shares)					1
Vesting period					1 year
Settlement period					30 days
DSU Awards \| Directors and Advisory Directors \| 2020 Equity Plan
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Granted (in shares)			39,846
Grant date fair value of the award			$ 0.9
Vesting percentage			100.00%
Period over which cost will be recognized			1 year

STOCK-BASED COMPENSATION - Schedule of Unamortized Stock-Based Compensation Expense (Details) - USD ($) $ in Thousands	9 Months Ended	12 Months Ended
	Sep. 30, 2025	Dec. 31, 2024
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Total unamortized stock-based compensation	$ 19,090	$ 10,317
SSARs
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Total unamortized stock-based compensation	114	0
RSU Awards
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Total unamortized stock-based compensation	11,402	7,093
PSU Awards
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Total unamortized stock-based compensation	7,146	3,043
DSU Awards
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Total unamortized stock-based compensation	$ 428	$ 181
Busey Awards \| 2020 Equity Plan
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Weighted average period over which expense is to be recognized on awards issued under Busey's 2020 Equity Plan	1 year 10 months 24 days	2 years 6 months
CrossFirst Awards
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Weighted average period over which expense is to be recognized on awards issued under Busey's 2020 Equity Plan	1 year 3 months 18 days

BORROWINGS - Schedule of Unamortized Debt Issuance Cost (Details) - USD ($) $ in Thousands	Sep. 30, 2025	Dec. 31, 2024
Debt Instrument [Line Items]
Total unamortized debt issuance costs	$ 707	$ 1,226
Subordinated notes issued in 2020 \| Subordinated Debt
Debt Instrument [Line Items]
Total unamortized debt issuance costs	0	222
Subordinated notes issued in 2022 \| Subordinated Debt
Debt Instrument [Line Items]
Total unamortized debt issuance costs	$ 707	$ 1,004

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 815
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-URI https://asc.fasb.org/1943274/2147480434/815-10-50-8A

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
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-Name Accounting Standards Codification
-Section S99
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Reference 3: http://www.xbrl.org/2009/role/commonPracticeRef
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Reference 4: http://www.xbrl.org/2009/role/commonPracticeRef
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Reference 5: http://www.xbrl.org/2009/role/commonPracticeRef
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-Paragraph 3
-Subparagraph (SX 210.12-04(a))
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Reference 6: http://www.xbrl.org/2009/role/commonPracticeRef
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-Subparagraph (SX 210.4-08(f))
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Reference 7: http://www.xbrl.org/2003/role/exampleRef
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Reference 8: http://www.xbrl.org/2003/role/disclosureRef
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Reference 9: http://www.xbrl.org/2003/role/exampleRef
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Reference 10: http://www.xbrl.org/2003/role/exampleRef
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Reference 13: http://www.xbrl.org/2003/role/disclosureRef
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Reference 14: http://www.xbrl.org/2003/role/disclosureRef
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Reference 16: http://www.xbrl.org/2003/role/disclosureRef
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Reference 18: http://www.xbrl.org/2003/role/disclosureRef
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Reference 19: http://www.xbrl.org/2003/role/disclosureRef
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Reference 24: http://www.xbrl.org/2003/role/disclosureRef
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Reference 25: http://www.xbrl.org/2003/role/disclosureRef
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Reference 26: http://www.xbrl.org/2003/role/disclosureRef
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Reference 27: http://www.xbrl.org/2003/role/disclosureRef
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Reference 28: http://www.xbrl.org/2003/role/disclosureRef
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Reference 29: http://www.xbrl.org/2003/role/disclosureRef
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Reference 30: http://www.xbrl.org/2009/role/commonPracticeRef
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Reference 31: http://www.xbrl.org/2009/role/commonPracticeRef
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-URI https://asc.fasb.org/1943274/2147482900/835-30-50-1

+ Details

STOCK-BASED COMPENSATION - Schedule of Changes in the Company's Stock Option Awards (Details) - USD ($) $ / shares in Units, $ in Thousands	9 Months Ended	12 Months Ended
	Sep. 30, 2025	Dec. 31, 2024
Shares
Outstanding at beginning of year (in shares)	15,106
Outstanding at end of year (in shares)	15,106	15,106
Exercisable at end of year (in shares)	15,106
Weighted- Average Exercise Price
Outstanding at beginning of year (in dollars per share)	$ 23.53
Outstanding at end of year (in dollars per share)	23.53	$ 23.53
Exercisable at end of year (in dollars per share)	$ 23.53
Weighted- Average Remaining Contractual Term
Weighted-average remaining contractual life, options outstanding	1 year 1 month 17 days	1 year 10 months 13 days
Weighted-average remaining contractual life, exercisable at end of year	1 year 1 month 17 days
Intrinsic value, options outstanding	$ 0	$ 1
Intrinsic value, exercisable at end of year	$ 0

MERGERS AND ACQUISITIONS (Tables)

9 Months Ended

Sep. 30, 2025

Business Combination, Asset Acquisition, Transaction between Entities under Common Control, and Joint Venture Formation [Abstract]

Schedule of Estimated Acquisition-Date Fair Values of the Assets Acquired and Liabilities Assumed

Acquisition-date fair values of the assets acquired and liabilities assumed, as well as the fair value of consideration transferred, were estimated as follows:


	As of
	March 1, 2025		April 1, 2024
(dollars in thousands)	CrossFirst (provisional)		M&M (final)
Assets acquired
Cash and cash equivalents	$	385,808	$	33,577
Securities	725,622		8,086
Portfolio loans, net of ACL	6,023,063		417,230
Premises and equipment	69,673		2,045

Other intangible assets	81,783		6,346
Other assets	212,832		10,461
Total assets acquired	7,498,781		477,745

Liabilities assumed
Deposits	6,571,699		392,838
Short-term borrowings	11,148		35,932
Long-term borrowings	68,922		1,450
Subordinated notes, net of unamortized issuance costs	—		3,911
Junior subordinated debt owed to unconsolidated trusts	2,238		2,594

Other liabilities	85,347		7,342
Total liabilities assumed	6,739,354		444,067

Net assets acquired	$	759,427	$	33,678

Consideration paid
Cash	$	4	$	15,200
Common stock	795,227		34,375
Preferred stock	7,750		—
Replacement awards1	5,999		—
Total consideration paid	$	808,980	$	49,575

Goodwill	$	49,553	$	15,897

___________________________________________

1.Represents the fair value of replacement equity awards issued to CrossFirst associates attributable to pre-combination service.

Schedule of Reconciliation Between the Purchase Price and the Fair Value

The following table provides a reconciliation between the purchase price and the fair value of these loans:


	As of
	March 1, 2025		April 1, 2024
(dollars in thousands)	CrossFirst		M&M
PCD Financial Assets
Gross contractual receivable for PCD financial assets	$	1,539,718	$	29,290
ACL recorded for estimated uncollectible contractual cash flows specific to PCD financial assets	(100,783)		(1,243)
Interest premium (discount) specific to PCD financial assets	(3,063)		(1,773)
Loans previously charged-off by CrossFirst	(110,740)		—
Fair value of PCD financial assets	$	1,325,132	$	26,274

Busey incurred acquisition related expenses as follows:


	Three Months Ended September 30,				Nine Months Ended September 30,
(dollars in thousands)	2025		2024		2025		2024
Pre-tax acquisition expenses
M&M	$	—	$	597	$	108	$	2,947
CrossFirst1	7,251		1,338		95,341		1,485
Pre-tax acquisition expenses1	$	7,251	$	1,935	$	95,449	$	4,432

___________________________________________

1.In addition to the acquisition costs presented in the table above, during the nine months ended September 30, 2025, Busey recorded a $4.0 million adjustment to the initial provision for unfunded commitments for CrossFirst acquisition-date balances based on revised estimates resulting from implementation of a new CECL model.

Of the total acquisition related expenses, the following legal, professional, and consulting costs were incurred to consummate the mergers:


	Three Months Ended September 30,				Nine Months Ended September 30,
(dollars in thousands)	2025		2024		2025		2024
Pre-tax costs to consummate the merger
M&M	$	—	$	(3)	$	—	$	147
CrossFirst	301		1,180		7,531		1,316
Pre-tax costs to consummate the merger	$	301	$	1,177	$	7,531	$	1,463

Schedule of Business Acquisition, Pro Forma Information

Only the merger related expenses that have been recognized are included in net income in the table below:


	Three Months Ended September 30,				Nine Months Ended September 30,
(dollars in thousands)	2025		2024		2025		2024
Revenue (net interest income plus noninterest income)	$	191,142	$	186,276	$	562,462	$	564,177
Net income	55,120		54,853		123,822		120,093

- Definition

Tabular disclosure of business combination. Includes, but is not limited to, recognized asset and liability.

+ References + Details

DERIVATIVE FINANCIAL INSTRUMENTS - Schedule of Reclassification of Unrealized Gains and Losses from OCI (Details) $ in Thousands	9 Months Ended
	Sep. 30, 2025 USD ($)
Interest Rate Swap \| Cash Flow Hedging \| Interest Income
Derivative [Line Items]
Unrealized gains (losses) expected to be reclassified from OCI to interest income	$ (716)

PORTFOLIO LOANS - Schedule of Risk Grades of Portfolio Loans, Further Sorted by Origination (Details) - USD ($) $ in Thousands	9 Months Ended	12 Months Ended
	Sep. 30, 2025	Dec. 31, 2024
Financing Receivable, Credit Quality Indicator [Line Items]
2025 / 2024	$ 1,958,780	$ 1,137,553
2025 / 2024, charge-off	2,946	9
2024 / 2023	1,909,295	1,129,573
2024 /2023, charge-off	13,830	15,011
2023 / 2022	1,863,616	1,485,489
2023 / 2022, charge-off	4,600	254
2022 / 2021	2,443,758	1,250,313
2022 / 2021, charge-off	1,481	3,099
2021 / 2020	1,685,752	619,027
2021 / 2020, charge-off	13,844	4
Prior	1,436,362	774,903
Prior, charge-off	11,379	1,189
Revolving Loans	2,300,703	1,300,229
Revolving Loans, charge-off	4,586	0
Total	13,598,266	7,697,087
Total, gross write-offs	52,666	19,566
Pass
Financing Receivable, Credit Quality Indicator [Line Items]
Total	11,824,501	6,764,070
Watch
Financing Receivable, Credit Quality Indicator [Line Items]
Total	1,291,575	756,610
Special Mention
Financing Receivable, Credit Quality Indicator [Line Items]
Total	332,765	92,296
Substandard
Financing Receivable, Credit Quality Indicator [Line Items]
Total	103,329	62,023
Substandard Non-accrual
Financing Receivable, Credit Quality Indicator [Line Items]
Total	46,096	22,088
Commercial loans
Financing Receivable, Credit Quality Indicator [Line Items]
Total	10,919,490	5,552,288
Commercial loans \| Pass
Financing Receivable, Credit Quality Indicator [Line Items]
Total	9,172,355	4,635,264
Commercial loans \| Watch
Financing Receivable, Credit Quality Indicator [Line Items]
Total	1,284,255	747,202
Commercial loans \| Special Mention
Financing Receivable, Credit Quality Indicator [Line Items]
Total	325,157	91,414
Commercial loans \| Substandard
Financing Receivable, Credit Quality Indicator [Line Items]
Total	100,564	59,480
Commercial loans \| Substandard Non-accrual
Financing Receivable, Credit Quality Indicator [Line Items]
Total	37,159	18,928
Commercial loans \| C&I and other commercial
Financing Receivable, Credit Quality Indicator [Line Items]
2025 / 2024	718,397	376,534
2025 / 2024, charge-off	1,246	0
2024 / 2023	823,427	206,282
2024 /2023, charge-off	2,626	14,980
2023 / 2022	534,565	215,489
2023 / 2022, charge-off	4,347	148
2022 / 2021	334,593	144,671
2022 / 2021, charge-off	1,440	22
2021 / 2020	263,957	76,789
2021 / 2020, charge-off	13,591	0
Prior	181,890	144,014
Prior, charge-off	11,254	303
Revolving Loans	1,539,042	740,736
Revolving Loans, charge-off	4,550	0
Total	4,395,871	1,904,515
Total, gross write-offs	39,054	15,453
Commercial loans \| C&I and other commercial \| Pass
Financing Receivable, Credit Quality Indicator [Line Items]
2025 / 2024	659,612	320,831
2024 / 2023	722,192	147,909
2023 / 2022	425,370	163,870
2022 / 2021	238,755	125,053
2021 / 2020	192,946	74,146
Prior	151,925	117,234
Revolving Loans	1,316,353	596,295
Total	3,707,153	1,545,338
Commercial loans \| C&I and other commercial \| Watch
Financing Receivable, Credit Quality Indicator [Line Items]
2025 / 2024	26,374	38,734
2024 / 2023	79,588	49,394
2023 / 2022	66,467	44,709
2022 / 2021	46,942	16,393
2021 / 2020	55,238	2,175
Prior	18,233	20,964
Revolving Loans	140,436	109,055
Total	433,278	281,424
Commercial loans \| C&I and other commercial \| Special Mention
Financing Receivable, Credit Quality Indicator [Line Items]
2025 / 2024	17,388	1,718
2024 / 2023	17,339	2,293
2023 / 2022	25,541	5,658
2022 / 2021	43,362	2,634
2021 / 2020	4,974	106
Prior	2,913	2,540
Revolving Loans	40,750	21,203
Total	152,267	36,152
Commercial loans \| C&I and other commercial \| Substandard
Financing Receivable, Credit Quality Indicator [Line Items]
2025 / 2024	10,422	15,186
2024 / 2023	1,965	6,545
2023 / 2022	16,543	788
2022 / 2021	4,216	591
2021 / 2020	10,159	320
Prior	3,771	2,424
Revolving Loans	27,033	11,895
Total	74,109	37,749
Commercial loans \| C&I and other commercial \| Substandard Non-accrual
Financing Receivable, Credit Quality Indicator [Line Items]
2025 / 2024	4,601	65
2024 / 2023	2,343	141
2023 / 2022	644	464
2022 / 2021	1,318	0
2021 / 2020	640	42
Prior	5,048	852
Revolving Loans	14,470	2,288
Total	29,064	3,852
Commercial loans \| CRE
Financing Receivable, Credit Quality Indicator [Line Items]
2025 / 2024	852,917	467,816
2025 / 2024, charge-off	1,297	0
2024 / 2023	567,657	488,528
2024 /2023, charge-off	11,057	0
2023 / 2022	852,985	828,525
2023 / 2022, charge-off	0	0
2022 / 2021	1,395,727	709,847
2022 / 2021, charge-off	0	2,999
2021 / 2020	1,000,602	389,461
2021 / 2020, charge-off	253	0
Prior	711,610	358,936
Prior, charge-off	0	315
Revolving Loans	42,597	26,451
Revolving Loans, charge-off	0	0
Total	5,424,095	3,269,564
Total, gross write-offs	12,607	3,314
Commercial loans \| CRE \| Pass
Financing Receivable, Credit Quality Indicator [Line Items]
2025 / 2024	631,171	291,503
2024 / 2023	487,489	354,591
2023 / 2022	703,228	755,266
2022 / 2021	1,216,265	645,994
2021 / 2020	776,293	356,867
Prior	600,081	314,340
Revolving Loans	38,990	25,457
Total	4,453,517	2,744,018
Commercial loans \| CRE \| Watch
Financing Receivable, Credit Quality Indicator [Line Items]
2025 / 2024	169,711	115,078
2024 / 2023	56,362	132,900
2023 / 2022	139,202	60,611
2022 / 2021	156,277	62,408
2021 / 2020	186,841	28,320
Prior	83,665	38,733
Revolving Loans	2,255	895
Total	794,313	438,945
Commercial loans \| CRE \| Special Mention
Financing Receivable, Credit Quality Indicator [Line Items]
2025 / 2024	50,239	39,252
2024 / 2023	23,098	643
2023 / 2022	5,093	8,020
2022 / 2021	14,139	1,395
2021 / 2020	37,467	4,165
Prior	16,067	1,517
Revolving Loans	1,134	49
Total	147,237	55,041
Commercial loans \| CRE \| Substandard
Financing Receivable, Credit Quality Indicator [Line Items]
2025 / 2024	1,714	6,983
2024 / 2023	708	355
2023 / 2022	914	4,628
2022 / 2021	9,046	50
2021 / 2020	0	95
Prior	8,628	4,346
Revolving Loans	218	50
Total	21,228	16,507
Commercial loans \| CRE \| Substandard Non-accrual
Financing Receivable, Credit Quality Indicator [Line Items]
2025 / 2024	82	15,000
2024 / 2023	0	39
2023 / 2022	4,548	0
2022 / 2021	0	0
2021 / 2020	1	14
Prior	3,169	0
Revolving Loans	0	0
Total	7,800	15,053
Commercial loans \| Real estate construction
Financing Receivable, Credit Quality Indicator [Line Items]
2025 / 2024	265,344	185,219
2025 / 2024, charge-off	0	0
2024 / 2023	372,376	140,905
2024 /2023, charge-off	0	0
2023 / 2022	128,667	12,205
2023 / 2022, charge-off	0	0
2022 / 2021	215,814	25,233
2022 / 2021, charge-off	0	0
2021 / 2020	32,838	2,213
2021 / 2020, charge-off	0	0
Prior	3,632	1,124
Prior, charge-off	0	0
Revolving Loans	80,853	11,310
Revolving Loans, charge-off	0	0
Total	1,099,524	378,209
Total, gross write-offs	0	0
Commercial loans \| Real estate construction \| Pass
Financing Receivable, Credit Quality Indicator [Line Items]
2025 / 2024	240,725	159,825
2024 / 2023	328,610	134,450
2023 / 2022	125,079	12,205
2022 / 2021	215,814	24,781
2021 / 2020	25,158	2,213
Prior	3,632	1,124
Revolving Loans	72,667	11,310
Total	1,011,685	345,908
Commercial loans \| Real estate construction \| Watch
Financing Receivable, Credit Quality Indicator [Line Items]
2025 / 2024	1,221	20,170
2024 / 2023	43,492	6,455
2023 / 2022	3,588	0
2022 / 2021	0	208
2021 / 2020	177	0
Prior	0	0
Revolving Loans	8,186	0
Total	56,664	26,833
Commercial loans \| Real estate construction \| Special Mention
Financing Receivable, Credit Quality Indicator [Line Items]
2025 / 2024	18,233	0
2024 / 2023	0	0
2023 / 2022	0	0
2022 / 2021	0	221
2021 / 2020	7,420	0
Prior	0	0
Revolving Loans	0	0
Total	25,653	221
Commercial loans \| Real estate construction \| Substandard
Financing Receivable, Credit Quality Indicator [Line Items]
2025 / 2024	5,165	5,224
2024 / 2023	0	0
2023 / 2022	0	0
2022 / 2021	0	0
2021 / 2020	62	0
Prior	0	0
Revolving Loans	0	0
Total	5,227	5,224
Commercial loans \| Real estate construction \| Substandard Non-accrual
Financing Receivable, Credit Quality Indicator [Line Items]
2025 / 2024	0	0
2024 / 2023	274	0
2023 / 2022	0	0
2022 / 2021	0	23
2021 / 2020	21	0
Prior	0	0
Revolving Loans	0	0
Total	295	23
Retail loans
Financing Receivable, Credit Quality Indicator [Line Items]
Total	2,678,776	2,144,799
Retail loans \| Pass
Financing Receivable, Credit Quality Indicator [Line Items]
Total	2,652,146	2,128,806
Retail loans \| Watch
Financing Receivable, Credit Quality Indicator [Line Items]
Total	7,320	9,408
Retail loans \| Special Mention
Financing Receivable, Credit Quality Indicator [Line Items]
Total	7,608	882
Retail loans \| Substandard
Financing Receivable, Credit Quality Indicator [Line Items]
Total	2,765	2,543
Retail loans \| Substandard Non-accrual
Financing Receivable, Credit Quality Indicator [Line Items]
Total	8,937	3,160
Retail loans \| CRE
Financing Receivable, Credit Quality Indicator [Line Items]
2025 / 2024	115,672	102,988
2025 / 2024, charge-off	85	0
2024 / 2023	139,066	238,099
2024 /2023, charge-off	0	0
2023 / 2022	309,565	371,259
2023 / 2022, charge-off	0	0
2022 / 2021	460,893	358,351
2022 / 2021, charge-off	0	0
2021 / 2020	382,205	148,260
2021 / 2020, charge-off	0	0
Prior	538,521	270,229
Prior, charge-off	51	168
Revolving Loans	250,324	207,271
Revolving Loans, charge-off	36	0
Total	2,196,246	1,696,457
Total, gross write-offs	172	168
Retail loans \| CRE \| Pass
Financing Receivable, Credit Quality Indicator [Line Items]
2025 / 2024	111,695	101,582
2024 / 2023	138,069	237,306
2023 / 2022	304,874	366,820
2022 / 2021	457,128	354,380
2021 / 2020	379,646	147,236
Prior	533,444	267,431
Revolving Loans	245,398	205,885
Total	2,170,254	1,680,640
Retail loans \| CRE \| Watch
Financing Receivable, Credit Quality Indicator [Line Items]
2025 / 2024	2,696	1,255
2024 / 2023	606	550
2023 / 2022	489	2,733
2022 / 2021	1,520	3,377
2021 / 2020	280	872
Prior	1,160	124
Revolving Loans	569	497
Total	7,320	9,408
Retail loans \| CRE \| Special Mention
Financing Receivable, Credit Quality Indicator [Line Items]
2025 / 2024	69	151
2024 / 2023	84	0
2023 / 2022	4,052	344
2022 / 2021	1,479	0
2021 / 2020	1,705	0
Prior	0	372
Revolving Loans	219	15
Total	7,608	882
Retail loans \| CRE \| Substandard
Financing Receivable, Credit Quality Indicator [Line Items]
2025 / 2024	1,000	0
2024 / 2023	0	243
2023 / 2022	111	1,018
2022 / 2021	447	503
2021 / 2020	489	0
Prior	712	776
Revolving Loans	0	3
Total	2,759	2,543
Retail loans \| CRE \| Substandard Non-accrual
Financing Receivable, Credit Quality Indicator [Line Items]
2025 / 2024	212	0
2024 / 2023	307	0
2023 / 2022	39	344
2022 / 2021	319	91
2021 / 2020	85	152
Prior	3,205	1,526
Revolving Loans	4,138	871
Total	8,305	2,984
Retail loans \| Retail other
Financing Receivable, Credit Quality Indicator [Line Items]
2025 / 2024	6,450	4,996
2025 / 2024, charge-off	318	9
2024 / 2023	6,769	55,759
2024 /2023, charge-off	147	31
2023 / 2022	37,834	58,011
2023 / 2022, charge-off	253	106
2022 / 2021	36,731	12,211
2022 / 2021, charge-off	41	78
2021 / 2020	6,150	2,304
2021 / 2020, charge-off	0	4
Prior	709	600
Prior, charge-off	74	403
Revolving Loans	387,887	314,461
Revolving Loans, charge-off	0	0
Total	482,530	448,342
Total, gross write-offs	833	631
Retail loans \| Retail other \| Pass
Financing Receivable, Credit Quality Indicator [Line Items]
2025 / 2024	6,415	4,996
2024 / 2023	6,769	55,665
2023 / 2022	37,741	57,944
2022 / 2021	36,632	12,207
2021 / 2020	6,150	2,304
Prior	703	589
Revolving Loans	387,482	314,461
Total	481,892	448,166
Retail loans \| Retail other \| Watch
Financing Receivable, Credit Quality Indicator [Line Items]
2025 / 2024	0
2024 / 2023	0
2023 / 2022	0
2022 / 2021	0
2021 / 2020	0
Prior	0
Revolving Loans	0
Total	0	0
Retail loans \| Retail other \| Special Mention
Financing Receivable, Credit Quality Indicator [Line Items]
2025 / 2024	0
2024 / 2023	0
2023 / 2022	0
2022 / 2021	0
2021 / 2020	0
Prior	0
Revolving Loans	0
Total	0	0
Retail loans \| Retail other \| Substandard
Financing Receivable, Credit Quality Indicator [Line Items]
2025 / 2024	0
2024 / 2023	0
2023 / 2022	0
2022 / 2021	0
2021 / 2020	0
Prior	6
Revolving Loans	0
Total	6	0
Retail loans \| Retail other \| Substandard Non-accrual
Financing Receivable, Credit Quality Indicator [Line Items]
2025 / 2024	35	0
2024 / 2023	0	94
2023 / 2022	93	67
2022 / 2021	99	4
2021 / 2020	0	0
Prior	0	11
Revolving Loans	405	0
Total	$ 632	$ 176

PORTFOLIO LOANS - Schedule of Performance of Modified Loans (Details) $ in Thousands	Sep. 30, 2025 USD ($)
Loans identified as impaired
Non-accrual	$ 4,038
Current
Loans identified as impaired
Loans modified during the last twelve months	41,374
30-89 Days
Loans identified as impaired
Loans modified during the last twelve months	0
90+ Days
Loans identified as impaired
Loans modified during the last twelve months	0
Commercial loans \| C&I and other commercial
Loans identified as impaired
Non-accrual	4,038
Commercial loans \| C&I and other commercial \| Current
Loans identified as impaired
Loans modified during the last twelve months	32,062
Commercial loans \| C&I and other commercial \| 30-89 Days
Loans identified as impaired
Loans modified during the last twelve months	0
Commercial loans \| C&I and other commercial \| 90+ Days
Loans identified as impaired
Loans modified during the last twelve months	0
Commercial loans \| CRE
Loans identified as impaired
Non-accrual	0
Commercial loans \| CRE \| Current
Loans identified as impaired
Loans modified during the last twelve months	4,147
Commercial loans \| CRE \| 30-89 Days
Loans identified as impaired
Loans modified during the last twelve months	0
Commercial loans \| CRE \| 90+ Days
Loans identified as impaired
Loans modified during the last twelve months	0
Commercial loans \| Real estate construction
Loans identified as impaired
Non-accrual	0
Commercial loans \| Real estate construction \| Current
Loans identified as impaired
Loans modified during the last twelve months	5,165
Commercial loans \| Real estate construction \| 30-89 Days
Loans identified as impaired
Loans modified during the last twelve months	0
Commercial loans \| Real estate construction \| 90+ Days
Loans identified as impaired
Loans modified during the last twelve months	$ 0

STOCK-BASED COMPENSATION (Tables)

9 Months Ended

Sep. 30, 2025

Share-Based Payment Arrangement [Abstract]

Schedule of Changes in the Company's Stock Option Awards

Busey has outstanding stock options assumed from a 2017 acquisition. A summary of the status of, and changes in, Busey's stock option awards for the nine months ended September 30, 2025, follows:


Options	Shares	Weighted- Average Exercise Price		Weighted- Average Remaining Contractual Term	Intrinsic Value ($000's)
Outstanding at December 31, 2024	15,106	$	23.53	1.87 years	$	1



Outstanding at September 30, 2025	15,106	23.53		1.13 years	—

Exercisable at September 30, 2025	15,106	23.53		1.13 years	—

Schedule of Share-Based Payment Arrangement, Stock Appreciation Right, Activity

A summary of SSAR activity during 2025 is presented below:


SSARs	Shares	Weighted- Average Exercise Price		Weighted- Average Remaining Contractual Term	Intrinsic Value ($000's)
Outstanding at December 31, 2024	—	$	—	—	$	—
Replacement of CrossFirst SSARs	424,390	15.78
Exercised1	(119,842)	13.31
Forfeited	(4,005)	16.00
Expired	(30,145)	23.23
Outstanding at September 30, 2025	270,398	16.04		5.23 years	1,922

Exercisable at September 30, 2025	249,747	15.62		5.17 years	1,881

___________________________________________

1. The aggregate intrinsic value of SSARs exercised during 2025 was $1.1 million.

Schedule of Share-Based Payment Award, Stock Appreciation Rights, Valuation Assumptions

The following table provides the range of assumptions used in the Monte Carlo simulations to value CrossFirst awards that were replaced at acquisition, the weighted average grant date fair value, and information related to SSARs exercised for the indicated periods, as well as the remaining compensation cost to be recognized and the period over which the amount will be recognized as of the dates indicated:


(dollars in thousands, except per share amounts)	Nine Months Ended September 30, 2025
Assumptions
Expected volatility1	29.10% – 36.70%
Expected dividends2	4.17%
Simulation term3, 4, 5	4.20 years – 5.69 years
Risk-free rate6	3.97% – 4.03%
Weighted average grant date fair value per share	$	8.94

___________________________________________

1.Expected volatility was calculated using a historical volatility of Busey’s stock price over a period commensurate with the simulation term of the SSARs.

2.The dividend yield was calculated using Busey’s annual dividend and closing stock price on the date of acquisition.

3.The simulation term was commensurate with the midpoint of the longest expected term across all SSARs and was impacted by expected exercise behavior and termination rate.

4.As a component of determining the simulation term, exercise was assumed to occur at the earlier of the midpoint of i) the greater of the weighted average time to vest or the time the options are in the money, and the time the SSARs expire, ii) 90 days following the occurrence of a termination, or iii) the end of the contractual term.

5.As a component of determining the simulation term, termination rate was assumed to be between 25% and 50% in the first year following the acquisition and 5% for every year thereafter.

6.The risk-free rate for the simulation term of the SSARs was based on the continuously compounded semi-annual zero-coupon U.S. Treasury rates.

Schedule of Changes in the Company's RSU, PSU, and DSU Awards

A summary of changes in Busey’s RSU awards for the nine months ended September 30, 2025, is as follows:


RSU Awards	Shares	Weighted- Average Grant Date Fair Value
Nonvested at December 31, 2024	1,066,772	$	21.80
Conversion of Busey ROATCE PSUs to RSUs	157,094	23.99
Replacement of CrossFirst RSUs and PSUs	341,048	23.99
Granted	366,487	22.22
Dividend equivalents earned	48,060	22.30
Vested	(451,041)	20.03
Forfeited	(133,212)	22.38
Nonvested at September 30, 2025	1,395,208	23.23

A summary of changes in Busey’s PSU awards for the nine months ended September 30, 2025, is as follows:


PSU Awards	Shares1	Weighted- Average Grant Date Fair Value
Nonvested at December 31, 2024	372,042	$	21.15
Modifications based on CrossFirst acquisition2	(181,828)	20.43
Granted	407,723	20.99
Dividend equivalents earned	125	20.83
Vested	(6,131)	20.87
Forfeited	(45,878)	20.95

Nonvested at September 30, 2025	546,053	21.29

___________________________________________

1.Shares for PSU awards represent target shares at the grant date.

2.Modifications include PSUs that were converted to RSUs as well as balance adjustments related to the 2023 TSR PSUs and the 2024 TSR PSUs.

A summary of changes in Busey’s DSU awards for the nine months ended September 30, 2025, is as follows:


DSU Awards	Shares	Weighted- Average Grant Date Fair Value
Nonvested at December 31, 2024	36,893	$	23.40
Granted	39,846	22.16
Dividend equivalents earned	6,447	22.73
Vested	(42,424)	23.33

Nonvested at September 30, 2025	40,762	22.15

Vested and outstanding at September 30, 2025	144,461	23.01

Schedule of Stock-Based Compensation Expense

Busey recognized compensation expense related to non-vested equity awards as summarized in the table below:


		Three Months Ended September 30,				Nine Months Ended September 30,
(dollars in thousands)	Location	2025		2024		2025		2024
Stock-based compensation expense

SSARs	Salaries, wages, and employee benefits	$	14	$	—	$	121	$	—
RSU awards	Salaries, wages, and employee benefits	2,600		1,057		8,296		3,012
PSU awards1	Salaries, wages, and employee benefits	1,381		976		3,826		2,037
DSU awards	Other expense	223		211		620		615
ESPP	Salaries, wages, and employee benefits	80		47		262		164
Total stock-based compensation expense		$	4,298	$	2,291	$	13,125	$	5,828

___________________________________________

1.Expense for PSU awards with a relative total stockholder return performance goal represents amounts based on target shares at the grant date. Expense for PSU awards with return on average tangible common equity and compounded annual revenue growth rate performance goals represents amounts based on target shares at the grant date, adjusted for performance expectations as of the date indicated.

Schedule of Unamortized Stock-Based Compensation Expense

Unamortized compensation expense related to non-vested equity awards is summarized in the table below:


	As of
(dollars in thousands)	September 30, 2025		December 31, 2024
Unamortized stock-based compensation
SSARs	$	114	$	—
RSU awards	11,402		7,093
PSU awards1	7,146		3,043
DSU awards	428		181
Total unamortized stock-based compensation	$	19,090	$	10,317

Weighted average period over which expense is to be recognized on awards issued under Busey's 2020 Equity Plan	1.9 years		2.5 years
Weighted average period over which expense is to be recognized on CrossFirst replacement awards	1.3 years		—

___________________________________________

1.Unamortized expense for PSU awards with a market-based total stockholder return performance goal represents amounts based on target shares at grant date. Unamortized expense for PSU awards with return on average tangible common equity and compounded annual revenue growth rate performance goals represents amounts based on target shares at grant date, adjusted for performance expectations as of the date indicated.

DEBT SECURITIES - Schedule of Additional Information on Debt Securities In Unrealized or Unrecognized Loss Position (Details) $ in Thousands	Sep. 30, 2025 USD ($) security	Dec. 31, 2024 USD ($) security
Available for Sale
Debt securities with gross unrealized or unrecognized losses, fair value \| $	$ 1,163,233	$ 1,466,743
Gross unrealized or unrecognized losses on debt securities \| $	$ 162,225	$ 230,325
Ratio of gross unrealized or unrecognized losses to debt securities with gross unrealized or unrecognized losses	13.90%	15.70%
Count of debt securities \| security	632	677
Count of debt securities in an unrealized or unrecognized loss position \| security	428	586
Held to Maturity
Debt securities with gross unrealized or unrecognized losses, fair value \| $	$ 659,471	$ 675,053
Gross unrealized or unrecognized losses on debt securities \| $	$ 125,350	$ 151,577
Ratio of gross unrealized or unrecognized losses to debt securities with gross unrealized or unrecognized losses	19.00%	22.50%
Count of debt securities \| security	55	55
Count of debt securities in an unrealized or unrecognized loss position \| security	55	55
Total
Debt securities with gross unrealized or unrecognized losses, fair value \| $	$ 1,822,704	$ 2,141,796
Gross unrealized or unrecognized losses on debt securities \| $	$ 287,575	$ 381,902
Ratio of gross unrealized or unrecognized losses to debt securities with gross unrealized or unrecognized losses	15.80%	17.80%
Count of debt securities \| security	687	732
Count of debt securities in an unrealized or unrecognized loss position \| security	483	641

SIGNIFICANT ACCOUNTING POLICIES - Narrative (Details)				9 Months Ended
SIGNIFICANT ACCOUNTING POLICIES - Narrative (Details)	May 20, 2025 $ / shares shares	Mar. 01, 2025 $ / shares shares	Apr. 01, 2024 USD ($)	Sep. 30, 2025 USD ($) segment shares	Dec. 31, 2024 USD ($) shares	Sep. 30, 2024 USD ($)
Debt Instrument [Line Items]
Total assets \| $				$ 18,188,628,000	$ 12,046,722,000
Preferred stock phares per depository share (in dollars per share) \| $ / shares	$ 0.025
Number of reportable segments \| segment				3
Number of operating segments \| segment				3
Income tax examination, penalties and interest accrued \| $				$ 100,000
Accruals for payments of interest and penalties \| $				$ 0		$ 0
Preferred shares issued (in shares) \| shares				222,750	0
Preferred stock redemption price per share (in dollars per share) \| $ / shares		$ 1,000
M&M \| 5.25% Notes Maturing December 4, 2030 \| Subordinated Debt
Debt Instrument [Line Items]
Principal balance \| $			$ 4,000,000
Fixed to floating interest rate (as a percent)			5.25%
Series A Preferred Stock
Debt Instrument [Line Items]
Preferred shares issued (in shares) \| shares		7,750
Preferred stock, dividend rate		8.00%
Preferred stock, liquidation preference (in dollars per share) \| $ / shares		$ 1,000
Preferred stock redemption price per share (in dollars per share) \| $ / shares		$ 1,000
Depository Shares
Debt Instrument [Line Items]
Preferred stock, liquidation preference (in dollars per share) \| $ / shares	$ 25
Stock issued depositary shares (in shares) \| shares	8,600,000
Series B Preferred Stock
Debt Instrument [Line Items]
Preferred stock, liquidation preference (in dollars per share) \| $ / shares	$ 1,000
Preferred stock redemption price per share (in dollars per share) \| $ / shares	$ 1,000
Derivative \| Collateral Pledged
Debt Instrument [Line Items]
Restricted cash and cash equivalents \| $				$ 14,400,000
Third-Party Service Provider
Debt Instrument [Line Items]
Restricted cash and cash equivalents \| $				13,600,000
Federal Reserve Bank
Debt Instrument [Line Items]
Restricted cash and cash equivalents \| $				$ 68,100,000

TAX CREDIT INVESTMENTS AND OTHER INVESTMENTS IN UNCONSOLIDATED ENTITIES (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2025	Sep. 30, 2024	Sep. 30, 2025	Sep. 30, 2024	Dec. 31, 2024
Schedule of Equity Method Investments [Line Items]
Investments in unconsolidated entities	$ 138,435		$ 138,435		$ 132,006
Deferred Income Taxes and Other Assets [Abstract]
Income tax credits and other tax benefits	4,446	$ 4,040	13,354	$ 11,941
Amortization of investments in tax-advantaged projects	3,968	$ 3,575	11,905	$ 10,593
Funded investments \| Other assets
Schedule of Equity Method Investments [Line Items]
Investments in unconsolidated entities	90,776		90,776		70,796
Unfunded investments \| Other assets
Schedule of Equity Method Investments [Line Items]
Investments in unconsolidated entities	47,659		47,659		61,210
Unfunded investments \| Other liabilities
Schedule of Equity Method Investments [Line Items]
Unfunded investment obligations	$ 47,659		$ 47,659		$ 61,210

OUTSTANDING COMMITMENTS AND CONTINGENT LIABILITIES - Narrative (Details) - Minimum $ in Millions	Jul. 02, 2025 USD ($)
Other Commitments [Line Items]
Estimated amount due	$ 28.0
Estimated amount due, interest	17.4
Estimated amount due, penalties	$ 0.3

OPERATING SEGMENTS AND RELATED INFORMATION - Schedule of Financial Results by Operating Segment (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2025	Sep. 30, 2024	Sep. 30, 2025	Sep. 30, 2024
Segment Reporting Information [Line Items]
Interest income	$ 244,505	$ 134,606	$ 658,766	$ 392,365
Intersegment interest income	0	0	0	0
Interest expense	89,368	51,959	246,715	151,332
Intersegment interest expense	0	0	0	0
Net interest income	155,137	82,647	412,051	241,033
Provision for credit losses	(985)	409	50,308	6,677
Net interest income after provision for credit losses	156,122	82,238	361,743	234,356
Noninterest income
All other noninterest income	7,908	7,054	10,191	17,475
Intersegment noninterest income	0	0	0	0
Total noninterest income	41,198	35,845	107,284	104,461
Revenue	196,335	118,492	519,335	345,494
Noninterest expense
Salaries, wages, and employee benefits	74,145	44,593	220,068	130,161
Data processing	9,714	6,910	33,310	20,560
Amortization of intangible assets	4,507	2,548	12,182	7,586
Interchange expense	1,336	1,352	3,976	4,696
All other noninterest expense	30,316	20,116	90,345	59,869
Intersegment noninterest expense	0	0	0	0
Total noninterest expense	120,018	75,519	359,881	222,872
Income (loss) before income taxes	77,302	42,564	109,146	115,945
Income taxes	20,204	10,560	34,634	30,359
Net income	57,098	32,004	74,512	85,586
Wealth management fees
Noninterest income
Noninterest income	17,184	15,378	51,325	46,844
Payment technology solutions
Noninterest income
Noninterest income	5,092	5,265	15,121	16,889
Treasury management services
Noninterest income
Noninterest income	4,598	2,201	12,596	6,247
Card services and ATM fees
Noninterest income
Noninterest income	4,799	3,557	13,388	9,947
Other service charges on deposit accounts
Noninterest income
Noninterest income	1,617	2,390	4,663	7,059
Other
Segment Reporting Information [Line Items]
Interest income	1	8	6	29
Intersegment interest income	(16)	(12)	(46)	(361)
Interest expense	2,844	4,348	11,427	13,272
Intersegment interest expense	(951)	(457)	(2,308)	(2,109)
Net interest income	(1,908)	(3,895)	(9,159)	(11,495)
Provision for credit losses	0	0	0	0
Net interest income after provision for credit losses	(1,908)	(3,895)	(9,159)	(11,495)
Noninterest income
All other noninterest income	1,772	833	7,469	917
Intersegment noninterest income	(1,007)	(658)	(2,449)	(1,816)
Total noninterest income	765	175	5,020	(899)
Revenue	(1,143)	(3,720)	(4,139)	(12,394)
Noninterest expense
Salaries, wages, and employee benefits	10,685	6,015	33,166	15,695
Data processing	63	130	255	437
Amortization of intangible assets	0	0	0	0
Interchange expense	0	0	0	0
All other noninterest expense	2,374	2,631	13,754	6,014
Intersegment noninterest expense	(5,635)	(4,014)	(17,743)	(12,008)
Total noninterest expense	7,487	4,762	29,432	10,138
Income (loss) before income taxes	(8,630)	(8,482)	(33,571)	(22,532)
Income taxes	(2,760)	(1,708)	(7,711)	(5,478)
Net income	(5,870)	(6,774)	(25,860)	(17,054)
Other \| Wealth management fees
Noninterest income
Noninterest income	0	0	0	0
Other \| Payment technology solutions
Noninterest income
Noninterest income	0	0	0	0
Other \| Treasury management services
Noninterest income
Noninterest income	0	0	0	0
Other \| Card services and ATM fees
Noninterest income
Noninterest income	0	0	0	0
Other \| Other service charges on deposit accounts
Noninterest income
Noninterest income	0	0	0	0
Banking \| Operating Segments
Segment Reporting Information [Line Items]
Interest income	244,504	134,598	658,760	392,336
Intersegment interest income	0	0	0	324
Interest expense	86,524	47,611	235,288	138,060
Intersegment interest expense	951	457	2,308	2,109
Net interest income	157,029	86,530	421,164	252,491
Provision for credit losses	(985)	409	50,308	6,677
Net interest income after provision for credit losses	158,014	86,121	370,856	245,814
Noninterest income
All other noninterest income	5,957	5,431	2,134	15,414
Intersegment noninterest income	564	372	1,232	1,004
Total noninterest income	17,535	13,951	34,013	39,671
Revenue	174,564	100,481	455,177	292,162
Noninterest expense
Salaries, wages, and employee benefits	53,264	29,615	157,237	87,358
Data processing	8,062	5,298	28,392	15,742
Amortization of intangible assets	4,292	2,268	11,497	6,705
Interchange expense	0	0	0	0
All other noninterest expense	26,706	16,273	72,693	49,954
Intersegment noninterest expense	4,346	2,879	14,167	8,605
Total noninterest expense	96,670	56,333	283,986	168,364
Income (loss) before income taxes	78,879	43,739	120,883	117,121
Income taxes	21,283	10,518	37,142	30,711
Net income	57,596	33,221	83,741	86,410
Banking \| Operating Segments \| Wealth management fees
Noninterest income
Noninterest income	0	0	0	0
Banking \| Operating Segments \| Payment technology solutions
Noninterest income
Noninterest income	0	0	0	0
Banking \| Operating Segments \| Treasury management services
Noninterest income
Noninterest income	4,598	2,201	12,596	6,247
Banking \| Operating Segments \| Card services and ATM fees
Noninterest income
Noninterest income	4,799	3,557	13,388	9,947
Banking \| Operating Segments \| Other service charges on deposit accounts
Noninterest income
Noninterest income	1,617	2,390	4,663	7,059
Wealth Management \| Operating Segments
Segment Reporting Information [Line Items]
Interest income	0	0	0	0
Intersegment interest income	0	0	0	0
Interest expense	0	0	0	0
Intersegment interest expense	0	0	0	0
Net interest income	0	0	0	0
Provision for credit losses	0	0	0	0
Net interest income after provision for credit losses	0	0	0	0
Noninterest income
All other noninterest income	183	791	594	1,145
Intersegment noninterest income	0	0	0	0
Total noninterest income	17,367	16,169	51,919	47,989
Revenue	17,367	16,169	51,919	47,989
Noninterest expense
Salaries, wages, and employee benefits	7,576	6,606	21,713	19,831
Data processing	658	544	1,873	1,591
Amortization of intangible assets	215	280	685	881
Interchange expense	0	0	0	0
All other noninterest expense	562	573	1,889	2,079
Intersegment noninterest expense	885	774	2,443	2,322
Total noninterest expense	9,896	8,777	28,603	26,704
Income (loss) before income taxes	7,471	7,392	23,316	21,285
Income taxes	1,793	1,774	5,596	5,108
Net income	5,678	5,618	17,720	16,177
Wealth Management \| Operating Segments \| Wealth management fees
Noninterest income
Noninterest income	17,184	15,378	51,325	46,844
Wealth Management \| Operating Segments \| Payment technology solutions
Noninterest income
Noninterest income	0	0	0	0
Wealth Management \| Operating Segments \| Treasury management services
Noninterest income
Noninterest income	0	0	0	0
Wealth Management \| Operating Segments \| Card services and ATM fees
Noninterest income
Noninterest income	0	0	0	0
Wealth Management \| Operating Segments \| Other service charges on deposit accounts
Noninterest income
Noninterest income	0	0	0	0
FirsTech \| Operating Segments
Segment Reporting Information [Line Items]
Interest income	0	0	0	0
Intersegment interest income	16	12	46	37
Interest expense	0	0	0	0
Intersegment interest expense	0	0	0	0
Net interest income	16	12	46	37
Provision for credit losses	0	0	0	0
Net interest income after provision for credit losses	16	12	46	37
Noninterest income
All other noninterest income	(4)	(1)	(6)	(1)
Intersegment noninterest income	443	286	1,217	812
Total noninterest income	5,531	5,550	16,332	17,700
Revenue	5,547	5,562	16,378	17,737
Noninterest expense
Salaries, wages, and employee benefits	2,620	2,357	7,952	7,277
Data processing	931	938	2,790	2,790
Amortization of intangible assets	0	0	0	0
Interchange expense	1,336	1,352	3,976	4,696
All other noninterest expense	674	639	2,009	1,822
Intersegment noninterest expense	404	361	1,133	1,081
Total noninterest expense	5,965	5,647	17,860	17,666
Income (loss) before income taxes	(418)	(85)	(1,482)	71
Income taxes	(112)	(24)	(393)	18
Net income	(306)	(61)	(1,089)	53
FirsTech \| Operating Segments \| Wealth management fees
Noninterest income
Noninterest income	0	0	0	0
FirsTech \| Operating Segments \| Payment technology solutions
Noninterest income
Noninterest income	5,092	5,265	15,121	16,889
FirsTech \| Operating Segments \| Treasury management services
Noninterest income
Noninterest income	0	0	0	0
FirsTech \| Operating Segments \| Card services and ATM fees
Noninterest income
Noninterest income	0	0	0	0
FirsTech \| Operating Segments \| Other service charges on deposit accounts
Noninterest income
Noninterest income	$ 0	$ 0	$ 0	$ 0

FAIR VALUE MEASUREMENTS - Schedule of Activity for Financial Assets Measured at Fair Value on a Recurring Basis (Details) - Fair Value, Recurring - Level 3 Inputs - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2025	Sep. 30, 2024	Sep. 30, 2025	Sep. 30, 2024
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair value, beginning balance	$ (45)	$ 8	$ 5	$ 15
Gains (losses) recognized in earnings	170	(5)	163	(15)
Purchases	(145)	13	(171)	16
Sales	0	0	24	0
Assumed in acquisition	0	0	(41)	0
Fair value, ending balance	$ (20)	$ 16	$ (20)	$ 16
Fair Value, Asset, Recurring Basis, Unobservable Input Reconciliation, Gain (Loss), Statement of Income or Comprehensive Income [Extensible Enumeration]	Other noninterest expense	Other noninterest expense	Other noninterest expense	Other noninterest expense

MERGERS AND ACQUISITIONS

9 Months Ended

Sep. 30, 2025

Business Combination, Asset Acquisition, Transaction between Entities under Common Control, and Joint Venture Formation [Abstract]

MERGERS AND ACQUISITIONS

NOTE 2. MERGERS AND ACQUISITIONS

CrossFirst Bankshares, Inc.

On March 1, 2025, Busey completed its acquisition of CrossFirst (NASDAQ: CFB), the holding company for CrossFirst Bank, pursuant to an Agreement and Plan of Merger, dated August 26, 2024, by and between Busey and CrossFirst (the “CrossFirst Merger Agreement”). This partnership creates a premier commercial bank in the Midwest, Southwest, and Florida, with 79 full-service locations across 10 states—Arizona, Colorado, Florida, Illinois, Indiana, Kansas, Missouri, New Mexico, Oklahoma, and Texas. The combined holding company continues to operate under the First Busey Corporation name. Busey’s common stock continues to trade on the Nasdaq under the “BUSE” stock ticker symbol.

Merger of CrossFirst Bank into Busey Bank

CrossFirst Bank’s results of operations were included in Busey’s consolidated results of operations beginning March 1, 2025. Busey operated CrossFirst Bank as a separate banking subsidiary until it was merged with and into Busey Bank on June 20, 2025. At the time of the bank merger, CrossFirst Bank’s banking centers became banking centers of Busey Bank.

CrossFirst Merger Consideration

Upon completion of the acquisition, each share of CrossFirst common stock converted into the right to receive 0.6675 of a share of Busey’s common stock. Cash was paid in lieu of fractional shares. The fair value of common shares issued in consideration of the CrossFirst acquisition was based on the closing price of Busey’s common stock on February 28, 2025.

Further, upon completion of the acquisition, each share of CrossFirst Series A Non-Cumulative Perpetual Preferred Stock converted to the right to receive one share of Busey Series A Preferred Stock. The fair value of Busey Series A Preferred Stock was based on the redemption price of $1,000 per share.

The total consideration paid also included the fair value of replacement equity awards related to past service totaling $6.0 million. Busey used a Monte Carlo simulation to estimate the fair value of SSARs and market-based awards. Other awards were valued based on Busey’s closing stock price on February 28, 2025.

Acquisition Accounting

The CrossFirst acquisition was accounted for using the acquisition method of accounting and, accordingly, assets acquired, liabilities assumed, and consideration exchanged were recorded at estimated fair values as of March 1, 2025, the date of acquisition. Subsequent to the acquisition, fair value adjustments of $1.8 million have been recorded, as additional information and valuations became available. Estimated fair values are considered provisional until final fair values are determined or the measurement period has passed, but no later than one year from the acquisition date. Review of all valuations and taxes are still being performed by management. Therefore, amounts are subject to change from the provisional amounts disclosed below.

As the total consideration paid for CrossFirst exceeded the estimated fair value of net assets acquired, goodwill of $49.6 million was recorded as a result of the acquisition. Goodwill recorded for this transaction reflects synergies expected from the acquisition and the greater revenue opportunities from Busey’s broader service capabilities in attractive new markets. Goodwill recorded for this transaction is not tax deductible and was assigned to the Banking operating segment.

Merchants and Manufacturers Bank Corporation

On April 1, 2024, Busey completed its acquisition of M&M and its wholly-owned subsidiary, M&M Bank, through a merger transaction. This partnership added M&M’s Life Equity Loan® products to Busey’s existing suite of services and expanded Busey’s presence in the suburban Chicago market.

Merger of M&M Bank into Busey Bank

M&M Bank’s results of operations were included in Busey’s results of operation beginning April 1, 2024. Busey operated M&M Bank as a separate banking subsidiary of Busey until it was merged with Busey Bank on June 21, 2024. At the time of the bank merger, M&M Bank’s banking centers became banking centers of Busey Bank, except for M&M’s banking center located at 990 Essington Rd., Joliet, Illinois, which was closed in connection with the bank merger.

M&M Merger Consideration

At the effective time of the M&M acquisition, each share of M&M common stock converted to the right to receive, at the election of each stockholder and subject to proration and adjustment as provided in the M&M merger agreement, either (1) $117.74 in cash (“Cash Election”), (2) 5.7294 shares of Busey common stock (“Share Election”), or (3) mixed consideration of $34.55 in cash and 4.0481 shares of Busey common stock (“Mixed Election”).

Most of the M&M common stockholders who submitted an election form by the election deadline made the Share Election to receive their merger consideration solely in the form of shares of Busey common stock. As a result of the elections of M&M common stockholders, and in accordance with the proration and adjustment provisions of the M&M merger agreement, the merger consideration paid to M&M common stockholders was comprised of an aggregate of 1,429,304 shares of Busey common stock and an aggregate of $12.2 million in cash, allocated as follows for each share of M&M stock: (1) $117.74 in cash for the Cash Election, (2) $5.3966 in cash and 5.4668 shares of Busey common stock for the Share Election, and (3) $34.55 in cash and 4.0481 shares of Busey common stock for the Mixed Election. Pursuant to the terms of the M&M merger agreement, M&M common stockholders that did not make an election or submit a properly completed election form by the election deadline of March 29, 2024, received cash consideration of $117.74 for each share of M&M common stock held. No fractional shares of Busey common stock were issued in the M&M acquisition. Fractional shares were paid in cash at the rate of $23.32 per share.

Additional merger consideration of $3.0 million was paid to redeem 300 shares of M&M preferred stock.

Acquisition Accounting

The M&M acquisition was accounted for using the acquisition method of accounting and, accordingly, assets acquired, liabilities assumed, and consideration exchanged were recorded at estimated fair values on April 1, 2024, the date of acquisition. A final fair value adjustment of $0.1 million for deferred taxes was recorded during the three months ended March 31, 2025, in connection with the M&M acquisition. Fair values, including initial accounting for deferred taxes, were subject to refinement for up to one year after the closing date as additional information regarding the closing date fair values became available. Fair values were final as of March 31, 2025.

As the total consideration paid for M&M exceeded the estimated fair value of net assets acquired, goodwill of $15.9 million was recorded as a result of the acquisition. Goodwill recorded for this transaction reflects synergies expected from the acquisition and expansion within the Chicago metropolitan market. Goodwill recorded for this transaction is not tax deductible and was assigned to the Banking operating segment.

Acquisition Date Fair Values

Acquisition-date fair values of the assets acquired and liabilities assumed, as well as the fair value of consideration transferred, were estimated as follows:


	As of
	March 1, 2025		April 1, 2024
(dollars in thousands)	CrossFirst (provisional)		M&M (final)
Assets acquired
Cash and cash equivalents	$	385,808	$	33,577
Securities	725,622		8,086
Portfolio loans, net of ACL	6,023,063		417,230
Premises and equipment	69,673		2,045

Other intangible assets	81,783		6,346
Other assets	212,832		10,461
Total assets acquired	7,498,781		477,745

Liabilities assumed
Deposits	6,571,699		392,838
Short-term borrowings	11,148		35,932
Long-term borrowings	68,922		1,450
Subordinated notes, net of unamortized issuance costs	—		3,911
Junior subordinated debt owed to unconsolidated trusts	2,238		2,594

Other liabilities	85,347		7,342
Total liabilities assumed	6,739,354		444,067

Net assets acquired	$	759,427	$	33,678

Consideration paid
Cash	$	4	$	15,200
Common stock	795,227		34,375
Preferred stock	7,750		—
Replacement awards1	5,999		—
Total consideration paid	$	808,980	$	49,575

Goodwill	$	49,553	$	15,897

___________________________________________

1.Represents the fair value of replacement equity awards issued to CrossFirst associates attributable to pre-combination service.

Valuations of Loans

Estimated fair values for the loan portfolio acquired in the CrossFirst acquisition includes adjustments to certain receivables that were not considered PCD as of the acquisition date. These fair value adjustments were determined using a discounted cash flow model that applies various assumptions about coupon rates, remaining maturities, prepayment speeds, projected default probabilities, losses given defaults, and estimates of prevailing discount rates. These loans did not show signs of deterioration since origination, and therefore, at the acquisition date, were not subject to the guidance related to PCD loans. Receivables acquired in the CrossFirst acquisition that were not subject to these requirements include non-PCD loans with a fair value of $4.70 billion and gross contractual amounts receivable of $4.79 billion.

A portion of acquired loans were PCD. The following table provides a reconciliation between the purchase price and the fair value of these loans:


	As of
	March 1, 2025		April 1, 2024
(dollars in thousands)	CrossFirst		M&M
PCD Financial Assets
Gross contractual receivable for PCD financial assets	$	1,539,718	$	29,290
ACL recorded for estimated uncollectible contractual cash flows specific to PCD financial assets	(100,783)		(1,243)
Interest premium (discount) specific to PCD financial assets	(3,063)		(1,773)
Loans previously charged-off by CrossFirst	(110,740)		—
Fair value of PCD financial assets	$	1,325,132	$	26,274

Pro Forma Results

The following unaudited pro forma information has been prepared as if the CrossFirst acquisition had occurred on January 1, 2024, and as if the M&M acquisition had occurred January 1, 2023. The pro forma results combine the historical results of CrossFirst and M&M into Busey’s Consolidated Statements of Income (Unaudited), including the impact of purchase accounting adjustments such as loan discount accretion, intangible assets amortization, and deposit accretion, net of taxes. The pro forma results have been prepared for comparative purposes only and are not necessarily indicative of the results that would have been obtained had the acquisitions actually occurred on January 1, 2024, or on January 1, 2023, as applicable. Further, pro forma information does not purport to be indicative of future financial operating results. No assumptions have been applied to the pro forma results of operations regarding possible revenue enhancements, expense efficiencies, or asset dispositions. Only the merger related expenses that have been recognized are included in net income in the table below:


	Three Months Ended September 30,				Nine Months Ended September 30,
(dollars in thousands)	2025		2024		2025		2024
Revenue (net interest income plus noninterest income)	$	191,142	$	186,276	$	562,462	$	564,177
Net income	55,120		54,853		123,822		120,093

Other Acquisition Costs

Busey incurred acquisition related expenses as follows:


	Three Months Ended September 30,				Nine Months Ended September 30,
(dollars in thousands)	2025		2024		2025		2024
Pre-tax acquisition expenses
M&M	$	—	$	597	$	108	$	2,947
CrossFirst1	7,251		1,338		95,341		1,485
Pre-tax acquisition expenses1	$	7,251	$	1,935	$	95,449	$	4,432

___________________________________________

Acquisition related expenses for CrossFirst were comprised primarily of an initial provision to establish an ACL on non-PCD loans (recorded as provision expense), and multiple components of noninterest expense including an initial provision for unfunded commitments; salaries, wages and employee benefits (including equity compensation); data processing; and legal, professional, and consulting costs. Acquisition related expenses for M&M were comprised primarily of professional fees and data processing costs.

Of the total acquisition related expenses, the following legal, professional, and consulting costs were incurred to consummate the mergers:


	Three Months Ended September 30,				Nine Months Ended September 30,
(dollars in thousands)	2025		2024		2025		2024
Pre-tax costs to consummate the merger
M&M	$	—	$	(3)	$	—	$	147
CrossFirst	301		1,180		7,531		1,316
Pre-tax costs to consummate the merger	$	301	$	1,177	$	7,531	$	1,463

- Definition

The entire disclosure for business combination.

+ References

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+ Details

BORROWINGS (Tables)

9 Months Ended

Sep. 30, 2025

Debt Disclosure [Abstract]

Schedule of Securities Sold Under Agreements to Repurchase

Securities sold under agreements to repurchase were as follows:


	As of
(dollars in thousands)	September 30, 2025			December 31, 2024
Securities sold under agreements to repurchase	$	147,152		$	155,610
Weighted average rate for securities sold under agreements to repurchase	2.50		%	2.63		%

Schedule of Long-term Borrowings

Long-term borrowings are presented in the table below:


	As of
(dollars in thousands)	September 30, 2025		December 31, 2024
Long-term borrowings

FHLB borrowings	$	79,174	$	—
Secured borrowings	6,991		—

Finance lease liabilities	6,266		—
Total long-term borrowings	$	92,431	$	—

Schedule of Unamortized Debt Issuance Cost

Unamortized debt issuance costs related to Busey’s subordinated notes are presented in the following table:


	As of
(dollars in thousands)	September 30, 2025		December 31, 2024
Unamortized debt issuance costs
Subordinated notes issued in 2020	$	—	$	222
Subordinated notes issued in 2022	707		1,004
Total unamortized debt issuance costs	$	707	$	1,226

- Definition

Tabular disclosure of long-debt instruments or arrangements, including identification, terms, features, collateral requirements and other information necessary to a fair presentation. These are debt arrangements that originally required repayment more than twelve months after issuance or greater than the normal operating cycle of the entity, if longer.

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+ Details

DERIVATIVE FINANCIAL INSTRUMENTS - Schedule of Net Gains (Losses) Relating to Derivative Instruments (Details) - Designated as Hedging Instrument - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2025	Sep. 30, 2024	Sep. 30, 2025	Sep. 30, 2024
Derivative [Line Items]
Net gains (losses) on mortgage banking derivatives	$ 163	$ 30	$ 583	$ 404
Interest rate lock commitments
Derivative [Line Items]
Net gains (losses) on mortgage banking derivatives	177	121	658	569
Forward sales commitments
Derivative [Line Items]
Net gains (losses) on mortgage banking derivatives	$ (14)	$ (91)	$ (75)	$ (165)

OUTSTANDING COMMITMENTS AND CONTINGENT LIABILITIES

9 Months Ended

Sep. 30, 2025

Commitments and Contingencies Disclosure [Abstract]

OUTSTANDING COMMITMENTS AND CONTINGENT LIABILITIES

NOTE 11. OUTSTANDING COMMITMENTS AND CONTINGENT LIABILITIES

Commitments and Credit Risk

A summary of the contractual amount of Busey’s exposure to off-balance sheet risk relating to the Company’s commitments follows:


	As of
(dollars in thousands)	September 30, 2025		December 31, 2024
Off-Balance Sheet Commitments
Commitments to extend credit	$	4,766,360	$	2,512,714
Standby letters of credit	132,385		35,464
Total commitments	$	4,898,745	$	2,548,178

Legal Matters

Busey is a party to legal actions which arise in the normal course of its business activities. Legal and administrative proceedings are subject to inherent uncertainties, and while unfavorable outcomes could occur, Busey does not believe at this time that any potential liabilities relating to pending or potential legal matters are likely to have a material impact on Busey's results of operations or financial position.

Franchise Tax Matter

In 2021, Busey received an inquiry from the Illinois Secretary of State, pursuant to which the Illinois Secretary of State asked for additional information regarding certain of Busey’s franchise tax filings and the calculation of amounts due thereunder. The franchise tax is established by the Illinois Business Corporation Act (“BCA”) 805 ILCS 5/1 et seq., and is a tax imposed on foreign and domestic corporations for the privilege of conducting business in Illinois. Busey has been cooperating with the inquiry and has delivered additional BCA forms requested by the Illinois Secretary of State, with a full reservation of rights by Busey, including seeking judicial relief, if necessary, with respect to any potential dispute regarding Busey’s preparation of the BCA forms and the calculation of the franchise taxes due.

On March 20, 2025, the Illinois Secretary of State requested that Busey resubmit the requested forms using a proposed methodology for paid-in capital that Busey views as inconsistent with the Illinois Secretary of State’s past practice, and existing statutory and case law. Accordingly, on May 14, 2025, within the Illinois Secretary of State’s requested timeframe, Busey informed the Illinois Secretary of State that it would not resubmit the requested forms with the methodology that Busey disputes and requested that the parties instead continue good faith discussions. On July 2, 2025, Busey received a notice of hearing from the Illinois Secretary of State indicating that an administrative hearing has been scheduled to “ascertain” the required amount of franchise taxes, penalties, interest, fees, and charges purportedly due from Busey to the Illinois Secretary of State. In the notice, the Illinois Secretary of State requested a determination of an amount due that the Illinois Secretary of State preliminarily estimated to be in excess of $28 million, including in excess of $17.4 million in interest and in excess of $0.3 million in penalties. Busey disagrees with the Illinois Secretary of State’s preliminary estimate and believes that the Illinois Secretary of State’s request is contrary not only to the Illinois Secretary of State’s past practice, but also existing statutory and case law. Busey intends to vigorously defend itself against the Illinois Secretary of State’s notice, including through appropriate judicial relief, if necessary. On July 31, 2025, First Busey filed a special appearance with the Illinois Secretary of State’s Department of Administrative Hearings solely for the limited purpose of contesting the jurisdiction of the Illinois Secretary of State to initiate and conduct the administrative hearing.

Where a loss is believed to be reasonably possible, but not probable, or the loss cannot be reasonably estimated, no accrual is required. Given the underlying disagreement between Busey and the Illinois Secretary of State on the proper methodology for calculating any franchise tax owed, the loss cannot be reasonably estimated. It is reasonably possible that this matter could require Busey to pay additional taxes, including potential penalties and interest, or make other expenditures or accrue liabilities in amounts that could not be reasonably estimated as of September 30, 2025. If the likelihood of potential liabilities elevates and Busey becomes able to reasonably estimate the loss, requiring an accrual, the potential future liabilities could be material in the period(s) in which they are recorded.

TAX CREDIT INVESTMENTS AND OTHER INVESTMENTS IN UNCONSOLIDATED ENTITIES

9 Months Ended

Sep. 30, 2025

Investments, All Other Investments [Abstract]

TAX CREDIT INVESTMENTS AND OTHER INVESTMENTS IN UNCONSOLIDATED ENTITIES

NOTE 9. TAX CREDIT INVESTMENTS AND OTHER INVESTMENTS IN UNCONSOLIDATED ENTITIES

Busey’s investments in unconsolidated entities and related unfunded investment obligations are reflected in other assets and other liabilities on the Consolidated Balance Sheets (Unaudited), and are summarized in the table below for the periods indicated:


		As of
(dollars in thousands)	Location	September 30, 2025		December 31, 2024
Investments in unconsolidated entities
Funded investments	Other assets	$	90,776	$	70,796
Unfunded investments	Other assets	47,659		61,210
Investments in unconsolidated entities		$	138,435	$	132,006

Unfunded investment obligations	Other liabilities	$	47,659	$	61,210

Upon adoption of ASU 2023-02 on January 1, 2024, Busey elected to apply the proportional amortization method in accounting for investments in tax-advantaged projects. Income tax credits and other tax benefits related to these investments, net of investment amortization, are included as a component of Busey’s estimated annual effective tax rate used for the calculation of income taxes presented on the Consolidated Statements of Income (Unaudited). Actual amounts of income tax credits and other benefits, along with the investment amortization, are presented in the table below:


	Three Months Ended September 30,				Nine Months Ended September 30,
(dollars in thousands)	2025		2024		2025		2024
Income tax credits and other tax benefits	$	4,446	$	4,040	$	13,354	$	11,941
Amortization of investments in tax-advantaged projects	3,968		3,575		11,905		10,593

DEBT SECURITIES - Narrative (Details) - USD ($) $ in Millions	Sep. 30, 2025	Dec. 31, 2024
Total pledged loans
Financial Instruments Owned and Pledged as Collateral [Line Items]
Debt securities, carrying amount	$ 741.8	$ 871.4

MERGERS AND ACQUISITIONS - Schedule of Pre-tax Costs to Consummate the Merger (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2025	Sep. 30, 2024	Sep. 30, 2025	Sep. 30, 2024
Business Combination [Line Items]
Pre-tax costs to consummate the merger	$ 301	$ 1,177	$ 7,531	$ 1,463
M&M
Business Combination [Line Items]
Pre-tax costs to consummate the merger	0	(3)	0	147
CrossFirst
Business Combination [Line Items]
Pre-tax costs to consummate the merger	$ 301	$ 1,180	$ 7,531	$ 1,316

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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Reference 35: http://www.xbrl.org/2003/role/disclosureRef
-Topic 805
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Subparagraph (b)(2)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479907/805-20-50-1

Reference 36: http://www.xbrl.org/2003/role/disclosureRef
-Topic 805
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Subparagraph (a)(1)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479907/805-20-50-1

Reference 37: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 805
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (g)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479328/805-10-50-2

Reference 38: http://www.xbrl.org/2003/role/disclosureRef
-Topic 805
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (g)(4)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479328/805-10-50-2

Reference 39: http://www.xbrl.org/2003/role/disclosureRef
-Topic 805
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (g)(3)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479328/805-10-50-2

Reference 40: http://www.xbrl.org/2003/role/disclosureRef
-Topic 805
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (g)(2)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479328/805-10-50-2

Reference 41: http://www.xbrl.org/2003/role/disclosureRef
-Topic 805
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (g)(1)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479328/805-10-50-2

Reference 42: http://www.xbrl.org/2003/role/disclosureRef
-Topic 805
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479328/805-10-50-2

+ Details

LEASES - Schedule of Lease Costs and Other Lease Information (Details) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2025 USD ($) lease	Sep. 30, 2024 USD ($)	Sep. 30, 2025 USD ($)	Sep. 30, 2024 USD ($)
Finance lease costs:
Amortization expense	$ 190	$ 0	$ 190	$ 0
Interest expense	187	0	187	0
Variable lease costs	15	15	45	43
Short-term lease costs	14	12	44	70
Total lease cost	1,897	635	4,709	1,815
Cash flows related to leases
Operating cash flows from operating leases	2,657	1,034	7,212	2,915
Operating cash flows from finance leases	187	0	187	0
Financing cash flows from finance leases	99	0	99	0
Right of use assets obtained in exchange for operating lease liabilities	(6,331)	469	23,287	1,478
Right of use assets obtained in exchange for finance lease liabilities	$ 6,365	0	6,365	0
Number of operating leases reclassified to finance leases during period \| lease	1
Net occupancy expense of premises
Operating lease costs:
Premises and Equipment rent expense	$ 1,483	604	4,221	1,692
Furniture and equipment expenses
Operating lease costs:
Premises and Equipment rent expense	$ 8	$ 4	22	10
CrossFirst
Cash flows related to leases
Right of use assets obtained in exchange for finance lease liabilities			6,400
Right of use assets obtained in exchange for operating lease liabilities			$ 23,200
M&M
Cash flows related to leases
Additional right of use assets obtained during the period in exchange for operating lease liabilities				700
Right of use assets obtained in exchange for operating lease liabilities				$ 100

DERIVATIVE FINANCIAL INSTRUMENTS - Schedule of Net Gains (Losses) Recorded in AOCI (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2025	Sep. 30, 2024	Sep. 30, 2025	Sep. 30, 2024
Derivative [Line Items]
Net gain (loss) recognized in OCI, net of tax	$ (486)	$ 10,404	$ 9,075	$ 295
(Gain) loss reclassified from OCI to interest expense, net of tax	2,304	2,364	6,629	6,988
Cash Flow Hedging \| Interest Rate Contract
Derivative [Line Items]
Net gain (loss) recognized in OCI, net of tax	(363)	7,439	6,876	211
(Gain) loss reclassified from OCI to interest income, net of tax	1,721	1,984	4,919	5,981
(Gain) loss reclassified from OCI to interest expense, net of tax	0	(294)	0	(985)
Net change in unrealized gains (losses) on cash flow hedges, net of tax	$ 1,358	$ 9,129	$ 11,795	$ 5,207

STOCK-BASED COMPENSATION - Schedule of Changes in the Company's RSU, PSU, and DSU Awards (Details)	9 Months Ended
	Sep. 30, 2025 $ / shares shares
RSU Awards
Shares
Non-vested at beginning of period (in shares) \| shares	1,066,772
Conversion of Busey ROATCE PSUs to RSUs (in shares) \| shares	157,094
Granted (in shares) \| shares	366,487
Dividend equivalents earned (in shares) \| shares	48,060
Vested (in shares) \| shares	(451,041)
Forfeited (in shares) \| shares	(133,212)
Non-vested at end of period (in shares) \| shares	1,395,208
Weighted- Average Grant Date Fair Value
Non-vested at beginning of period (in dollars per share) \| $ / shares	$ 21.80
Conversion of Busey ROATCE PSUs to RSUs (in dollars per share) \| $ / shares	23.99
Granted (in dollars per share) \| $ / shares	22.22
Dividend equivalents earned (in dollars per share) \| $ / shares	22.30
Vested (in dollars per share) \| $ / shares	20.03
Forfeited (in dollars per share) \| $ / shares	22.38
Non-vested at end of period (in dollars per share) \| $ / shares	$ 23.23
RSU Awards \| CrossFirst
Shares
Replacement of CrossFirst RSUs and PSUs (in shares) \| shares	341,048
Weighted- Average Grant Date Fair Value
Replacement of CrossFirst RSUs and PSUs (in dollars per share) \| $ / shares	$ 23.99
PSU Awards
Shares
Non-vested at beginning of period (in shares) \| shares	372,042
Modifications based on CrossFirst acquisition (in shares) \| shares	(181,828)
Granted (in shares) \| shares	407,723
Dividend equivalents earned (in shares) \| shares	125
Vested (in shares) \| shares	(6,131)
Forfeited (in shares) \| shares	(45,878)
Non-vested at end of period (in shares) \| shares	546,053
Weighted- Average Grant Date Fair Value
Non-vested at beginning of period (in dollars per share) \| $ / shares	$ 21.15
Modifications based on CrossFirst acquisition (in dollars per share) \| $ / shares	20.43
Granted (in dollars per share) \| $ / shares	20.99
Dividend equivalents earned (in dollars per share) \| $ / shares	20.83
Vested (in dollars per share) \| $ / shares	20.87
Forfeited (in dollars per share) \| $ / shares	20.95
Non-vested at end of period (in dollars per share) \| $ / shares	$ 21.29
DSU Awards
Shares
Non-vested at beginning of period (in shares) \| shares	36,893
Granted (in shares) \| shares	39,846
Dividend equivalents earned (in shares) \| shares	6,447
Vested (in shares) \| shares	(42,424)
Non-vested at end of period (in shares) \| shares	40,762
Vested and outstanding at end of period (in shares) \| shares	144,461
Weighted- Average Grant Date Fair Value
Non-vested at beginning of period (in dollars per share) \| $ / shares	$ 23.40
Granted (in dollars per share) \| $ / shares	22.16
Dividend equivalents earned (in dollars per share) \| $ / shares	22.73
Vested (in dollars per share) \| $ / shares	23.33
Non-vested at end of period (in dollars per share) \| $ / shares	22.15
Vested and outstanding at end of period (in dollars per share) \| $ / shares	$ 23.01

DEPOSITS - Schedule of Composition of Deposits (Details) - USD ($) $ in Thousands	Sep. 30, 2025	Dec. 31, 2024
Deposits [Abstract]
Noninterest-bearing demand deposits	$ 3,554,936	$ 2,719,907
Interest-bearing transaction deposits	3,171,255	2,423,237
Saving deposits and money market deposits	5,910,183	3,348,711
Time deposits	2,433,788	1,490,635
Total deposits	15,070,162	9,982,490
Brokered interest-bearing transaction deposits	50,240	0
Brokered savings deposits and money market deposits	10,000	6,002
Brokered time deposits	65,192	7,088
Aggregate amount of time deposits with a minimum denomination of $100,000	1,621,232	860,193
Aggregate amount of time deposits with a minimum denomination that meets or exceeds the FDIC insurance limit of $250,000	$ 807,378	$ 334,503

DERIVATIVE FINANCIAL INSTRUMENTS (Tables)

9 Months Ended

Sep. 30, 2025

Derivative Instruments and Hedging Activities Disclosure [Abstract]

Schedule of Financial Instruments Owned and Pledged as Collateral

Busey has executed a blanket lien with the FHLB. The principal balance of loans Busey has pledged as collateral with the FHLB and Federal Reserve Bank for liquidity, which Busey is able to borrow against, is set forth in the table below:


	As of
(dollars in thousands)	September 30, 2025		December 31, 2024
Pledged loans
FHLB	$	5,018,506	$	4,813,600
Federal Reserve Bank	1,973,933		765,824
Total pledged loans	$	6,992,439	$	5,579,424

To secure its obligations under derivative contracts, Busey pledged cash and held collateral as follows:


	As of
(dollars in thousands)	September 30, 2025		December 31, 2024
Cash pledged to secure obligations under derivative contracts	$	14,400	$	21,900
Collateral held to secure obligations under derivative contracts	8,140		20,260

Schedule of the Interest-Rate Swaps Designated as Cash Flow Hedges

A summary of the interest-rate swaps designated as cash flow hedges is presented below:


		As of
(dollars in thousands)	Location	September 30, 2025			December 31, 2024
Prime Loan Swap
Notional amount		$	300,000		$	300,000
Weighted average rate: receive-fixed		4.81		%	4.81		%
Weighted average variable Prime pay rates		7.37		%	7.62		%
Weighted average maturity		3.35 years			4.10 years

SOFR Loan Swaps
Notional amount		$	200,000		$	200,000
Weighted average rate: receive-fixed		3.78		%	3.78		%
Weighted average variable 1-month CME Term SOFR pay rates		4.25		%	—
Weighted average maturity		4.01 years			4.76 years

Gross aggregate fair value of the swaps
Gross aggregate fair value of swap assets	Other assets	$	3,617		$	—
Gross aggregate fair value of swap liabilities	Other liabilities	15,670			27,770

Balances carried in AOCI
Unrealized gains (losses) on cash flow hedges, net of tax	AOCI	$	(8,010)		$	(19,805)

Schedule of Reclassification of Unrealized Gains and Losses from OCI

During the next 12 months, Busey expects to reclassify unrealized gains and losses from OCI to interest income as shown in the following table. Amounts actually recognized could differ from these expectations due to changes in interest rates, hedge de-designations, and the addition of other hedges subsequent to September 30, 2025.


(dollars in thousands)	As of September 30, 2025

Unrealized gains (losses) expected to be reclassified from OCI to interest income	$	(716)

Schedule of Interest Income (Expense) Recorded on Swap Transactions

Interest income and interest expense recorded on these swap transactions is presented in the following table:


	Three Months Ended September 30,				Nine Months Ended September 30,
(dollars in thousands)	2025		2024		2025		2024
Interest on swap transactions
Increase (decrease) in interest income on swap transactions	$	(2,304)	$	(2,776)	$	(6,629)	$	(8,366)
(Increase) decrease in interest expense on swap transactions	—		412		—		1,378
Net increase (decrease) in net interest income on swap transactions	$	(2,304)	$	(2,364)	$	(6,629)	$	(6,988)

Schedule of Net Gains (Losses) Relating to these Derivative Instruments

Net gains (losses) relating to cash flow derivative instruments that were recorded in OCI on the Consolidated Statements of Income (Unaudited) are presented in the table below:


	Three Months Ended September 30,				Nine Months Ended September 30,
(dollars in thousands)	2025		2024		2025		2024
Unrealized gains (losses) on cash flow hedges
Net gain (loss) recognized in OCI, net of tax	$	(363)	$	7,439	$	6,876	$	211
(Gain) loss reclassified from OCI to interest income, net of tax	1,721		1,984		4,919		5,981
(Gain) loss reclassified from OCI to interest expense, net of tax	—		(294)		—		(985)
Net change in unrealized gains (losses) on cash flow hedges, net of tax	$	1,358	$	9,129	$	11,795	$	5,207

Changes in fair value of these derivative assets and liabilities are included in the Consolidated Statements of Income (Unaudited) and are summarized as follows:


		Three Months Ended September 30,				Nine Months Ended September 30,
(dollars in thousands)	Location	2025		2024		2025		2024
Interest rate swaps
Receive-fixed, pay-floating	Noninterest expense	$	(1,083)	$	(9,224)	$	(21)	$	(3,050)
Receive-floating, pay-fixed	Noninterest expense	1,083		9,224		21		3,050
Net change in fair value of interest rate swaps		$	—	$	—	$	—	$	—

Gains and losses relating to these derivative instruments are reported in noninterest income, and are summarized as follows for the periods presented:


		Three Months Ended September 30,				Nine Months Ended September 30,
(dollars in thousands)	Location	2025		2024		2025		2024
Net gains (losses) on mortgage banking derivatives
Gains (losses) on interest rate lock commitments	Mortgage revenue	$	177	$	121	$	658	$	569
Gains (losses) on forward sales commitments	Mortgage revenue	(14)		(91)		(75)		(165)


Net gains (losses) on mortgage banking derivatives		$	163	$	30	$	583	$	404

Schedule of Fair Values of Derivative Assets and Liabilities Recorded in Consolidated Balance Sheet

Amounts and fair values of derivative assets and derivative liabilities related to customer interest rate swaps recorded on the Consolidated Balance Sheets (Unaudited) are summarized as follows:


		As of September 30, 2025				As of December 31, 2024
(dollars in thousands)	Location	Notional Amount		Fair Value		Notional Amount		Fair Value
Derivative assets not designated as hedging instruments
Interest rate swaps: receive-fixed, pay-floating	Other assets	$	521,477	$	10,746	$	156,539	$	1,465
Interest rate swaps: receive-floating, pay-fixed	Other assets	487,107		19,420		562,697		28,854
Derivative assets not designated as hedging instruments		$	1,008,584	$	30,166	$	719,236	$	30,319

Derivative liabilities not designated as hedging instruments
Interest rate swaps: receive-fixed, pay-floating	Other liabilities	$	487,107	$	19,420	$	562,697	$	28,854
Interest rate swaps: receive-floating, pay-fixed	Other liabilities	521,477		10,746		156,539		1,465
Derivative liabilities not designated as hedging instruments		$	1,008,584	$	30,166	$	719,236	$	30,319

Amounts and fair values of mortgage banking derivatives included on the Consolidated Balance Sheets (Unaudited) are summarized as follows:


		As of September 30, 2025				As of December 31, 2024
(dollars in thousands)	Location	Notional Amount		Fair Value		Notional Amount		Fair Value
Mortgage banking derivative assets
Interest rate lock commitments	Other assets	$	6,515	$	132	$	2,430	$	28
Forward sales commitments	Other assets	4,679		19		3,457		21
Mortgage banking derivative assets		$	11,194	$	151	$	5,887	$	49

Mortgage banking derivative liabilities
Interest rate lock commitments	Other liabilities	$	—	$	—	$	436	$	4
Forward sales commitments	Other liabilities	9,290		78		1,955		6
Mortgage banking derivative liabilities		$	9,290	$	78	$	2,391	$	10

Schedule of Notional Amount and Fair Value of Risk Participation Agreement

The risk participation agreements mature between October 2025 and August 2030, and are summarized as follows:


	As of
(dollars in thousands)	September 30, 2025		December 31, 2024
Risk participation agreements purchased
Number of risk participation agreements	12		5
Notional amount	$	73,919	$	40,092
Fair value	39		5

Risk participation agreements sold
Number of risk participation agreements	12		—
Notional amount	$	106,453	$	—
Fair value	59		—

SIGNIFICANT ACCOUNTING POLICIES - Schedule of Stock Issuances (Details) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2025	Sep. 30, 2024	Sep. 30, 2025	Sep. 30, 2024	Dec. 31, 2024
Class of Stock [Line Items]
Preferred stock, par value (in dollars per share)	$ 0.001		$ 0.001		$ 0.001
Preferred stock, shares authorized (in shares)	1,000,000		1,000,000		1,000,000
Preferred shares issued (in shares)	222,750		222,750		0
Preferred shares outstanding (in shares)	222,750		222,750		0
Preferred stock, value, issued	$ 0		$ 0		$ 0
Preferred stock, liquidation preference	$ 222,750,000		222,750,000
Issuance of preferred stock, net of issuance costs			$ 207,447,000
Series A Non-Cumulative Perpetual Preferred Stock
Class of Stock [Line Items]
Preferred stock, shares authorized (in shares)	7,750		7,750
Preferred shares issued (in shares)	7,750		7,750
Preferred shares outstanding (in shares)	7,750		7,750
Preferred stock, value, issued	$ 7.75		$ 7.75
Preferred stock, value, outstanding	$ 7.75		$ 7.75
Preferred stock, liquidation preference (in dollars per share)	$ 1,000		$ 1,000
Preferred stock, liquidation preference	$ 7,750,000		$ 7,750,000
Issuance of preferred stock, net of issuance costs	$ 0	$ 0	$ 7.75	$ 0
8.25% Fixed-Rate Series B Non-Cumulative Perpetual Preferred Stock [Member]
Class of Stock [Line Items]
Preferred stock, dividend rate			8.25%
Preferred stock, shares authorized (in shares)	230,000		230,000
Preferred shares issued (in shares)	215,000		215,000
Preferred shares outstanding (in shares)	215,000		215,000
Preferred stock, value, issued	$ 215.00		$ 215.00
Preferred stock, value, outstanding	$ 215.00		$ 215.00
Preferred stock, liquidation preference (in dollars per share)	$ 1,000		$ 1,000
Preferred stock, liquidation preference	$ 215,000,000		$ 215,000,000
Issuance of preferred stock, net of issuance costs	$ 0	$ 0	$ 215.00	$ 0

STOCK-BASED COMPENSATION - Stock Settled Appreciation Rights (Details) - SSARs - USD ($) $ in Millions		9 Months Ended
	Mar. 01, 2025	Sep. 30, 2025
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Fair value of SSARs that have vested		$ 3.6
CrossFirst \| Common \| CrossFirst
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Shares received for each share owned (in shares)	0.6675
Omnibus Incentive 2018 Plan
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Vesting period		7 years
Weighted average remaining contractual term		5 years 4 months 24 days
Period over which cost will be recognized		3 years 2 months 12 days
Omnibus Incentive 2018 Plan \| Minimum
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Share-based compensation, expiration period		10 years
Omnibus Incentive 2018 Plan \| Maximum
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Share-based compensation, expiration period		15 years

DERIVATIVE FINANCIAL INSTRUMENTS - Schedule of Interest Income (Expense) Recorded on Swap Transactions (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2025	Sep. 30, 2024	Sep. 30, 2025	Sep. 30, 2024
Derivative [Line Items]
Net interest income	$ 155,137	$ 82,647	$ 412,051	$ 241,033
Interest Rate Swap \| Cash Flow Hedging
Derivative [Line Items]
Increase (decrease) in interest income on swap transactions	(2,304)	(2,776)	(6,629)	(8,366)
(Increase) decrease in interest expense on swap transactions	0	412	0	1,378
Net interest income	$ (2,304)	$ (2,364)	$ (6,629)	$ (6,988)

EARNINGS PER COMMON SHARE - Schedule of Average Shares Excluded From Computation of Diluted Earnings Per Common Share (Details) - shares	3 Months Ended		9 Months Ended
	Sep. 30, 2025	Sep. 30, 2024	Sep. 30, 2025	Sep. 30, 2024
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Total anti-dilutive common stock equivalents (in shares)	298,211	107,065	249,668	120,073
Options
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Total anti-dilutive common stock equivalents (in shares)	0	0	10,071	12,784
RSU Awards
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Total anti-dilutive common stock equivalents (in shares)	0	0	1,498	4,288
PSU Awards
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Total anti-dilutive common stock equivalents (in shares)	298,211	107,065	238,099	103,001

FAIR VALUE MEASUREMENTS - Schedule of Quantitative Information About Level 3 Fair Value Measurements (Details) - Fair Value, Nonrecurring $ in Thousands	Sep. 30, 2025 USD ($)	Dec. 31, 2024 USD ($)
Fair Value
Loans evaluated individually, net of related allowance	$ 19,056	$ 616
Bank property held for sale with impairment	2,099	2,841
OREO and other repossessed assets with subsequent impairment
Fair Value
OREO and other repossessed assets with subsequent impairment	2,628
Level 3 Inputs
Fair Value
Loans evaluated individually, net of related allowance	19,056	616
Bank property held for sale with impairment	2,099	2,841
Level 3 Inputs \| OREO and other repossessed assets with subsequent impairment
Fair Value
OREO and other repossessed assets with subsequent impairment	2,628
Level 3 Inputs \| Appraisal of collateral
Fair Value
Loans evaluated individually, net of related allowance	19,056	616
Level 3 Inputs \| Appraisal of collateral \| OREO and other repossessed assets with subsequent impairment
Fair Value
OREO and other repossessed assets with subsequent impairment	2,628
Level 3 Inputs \| Appraisal of collateral or real estate listing price
Fair Value
Bank property held for sale with impairment	$ 2,099	$ 2,841
Measurement Input, Comparability Adjustment \| Level 3 Inputs \| Appraisal of collateral \| Minimum
Range (Weighted Average)
Loans evaluated individually, net of related allowance	(0.016)	(0.250)
Measurement Input, Comparability Adjustment \| Level 3 Inputs \| Appraisal of collateral \| Minimum \| OREO and other repossessed assets with subsequent impairment
Range (Weighted Average)
OREO and other repossessed assets with subsequent impairment	(0.066)
Measurement Input, Comparability Adjustment \| Level 3 Inputs \| Appraisal of collateral \| Maximum
Range (Weighted Average)
Loans evaluated individually, net of related allowance	(1.000)	(1.000)
Measurement Input, Comparability Adjustment \| Level 3 Inputs \| Appraisal of collateral \| Maximum \| OREO and other repossessed assets with subsequent impairment
Range (Weighted Average)
OREO and other repossessed assets with subsequent impairment	(0.241)
Measurement Input, Comparability Adjustment \| Level 3 Inputs \| Appraisal of collateral \| Weighted Average
Range (Weighted Average)
Loans evaluated individually, net of related allowance	(0.322)	(0.749)
Measurement Input, Comparability Adjustment \| Level 3 Inputs \| Appraisal of collateral \| Weighted Average \| OREO and other repossessed assets with subsequent impairment
Range (Weighted Average)
OREO and other repossessed assets with subsequent impairment	(0.070)
Measurement Input, Comparability Adjustment \| Level 3 Inputs \| Appraisal of collateral or real estate listing price \| Minimum
Range (Weighted Average)
Bank property held for sale with impairment	(0.090)	(0.090)
Measurement Input, Comparability Adjustment \| Level 3 Inputs \| Appraisal of collateral or real estate listing price \| Maximum
Range (Weighted Average)
Bank property held for sale with impairment	(0.868)	(0.767)
Measurement Input, Comparability Adjustment \| Level 3 Inputs \| Appraisal of collateral or real estate listing price \| Weighted Average
Range (Weighted Average)
Bank property held for sale with impairment	(0.573)	(0.518)

OUTSTANDING COMMITMENTS AND CONTINGENT LIABILITIES (Tables)

9 Months Ended

Sep. 30, 2025

Commitments and Contingencies Disclosure [Abstract]

Schedule of Contractual Amount of Exposure to Off-Balance-Sheet Risk

A summary of the contractual amount of Busey’s exposure to off-balance sheet risk relating to the Company’s commitments follows:


	As of
(dollars in thousands)	September 30, 2025		December 31, 2024
Off-Balance Sheet Commitments
Commitments to extend credit	$	4,766,360	$	2,512,714
Standby letters of credit	132,385		35,464
Total commitments	$	4,898,745	$	2,548,178

LEASES (Tables)

9 Months Ended

Sep. 30, 2025

Leases [Abstract]

Schedule of Lease-Related Balances

The following table summarizes lease-related balances that Busey reported on its Consolidated Balance Sheets (Unaudited):


		As of
(dollars in thousands)	Location	September 30, 2025		December 31, 2024
Lease balances
Right of use assets:
Operating leases	Other assets	$	29,236	$	10,608
Finance leases	Premises and equipment, net	5,235		—
Total right of use assets		$	34,471	$	10,608

Lease liabilities:
Operating leases	Other liabilities	$	31,592	$	11,040
Finance leases	Long-term borrowings	6,266		—
Total lease liabilities		$	37,858	$	11,040

Lease terms are summarized as follows:

As of

September 30,
2025

December 31,
2024

Lease terms

Weighted average remaining lease terms

Operating leases

7.28 years

7.55 years

Finance leases

16.51 years

N/A

Weighted average discount rates

Operating leases

4.22

3.77

Finance leases

5.10

N/A

Schedule of Lease Costs and Other Lease Information

The following table presents lease costs that Busey reported on its Consolidated Statements of Income (Unaudited):


		Three Months Ended September 30,				Nine Months Ended September 30,
(dollars in thousands)	Location	2025		2024		2025		2024
Lease costs
Operating lease costs:
Premises rent expense	Net occupancy expense of premises	$	1,483	$	604	$	4,221	$	1,692
Equipment rent expense	Furniture and equipment expenses	8		4		22		10
Finance lease costs:
Amortization expense	Net occupancy expense of premises	190		—		190		—
Interest expense	Long-term borrowings	187		—		187		—
Variable lease costs	Net occupancy expense of premises	15		15		45		43
Short-term lease costs	Net occupancy expense of premises	14		12		44		70
Total lease cost		$	1,897	$	635	$	4,709	$	1,815

Cash paid for amounts included in the measurement of lease liabilities was as follows:


	Three Months Ended September 30,				Nine Months Ended September 30,
(dollars in thousands)	2025		2024		2025		2024
Cash flows related to leases


Operating cash flows from operating leases	$	2,657	$	1,034	$	7,212	$	2,915
Operating cash flows from finance leases	187		—		187		—
Financing cash flows from finance leases	99		—		99		—

Right of use assets obtained in exchange for operating lease liabilities1	(6,331)		469		23,287		1,478
Right of use assets obtained in exchange for finance lease liabilities1	6,365		—		6,365		—

___________________________________________

1.The nine months ended September 30, 2025, included $23.2 million for operating and $6.4 million for financing right of use assets recognized in connection with the acquisition of CrossFirst. One finance lease was initially classified as operating, and was moved to a financing classification in the third quarter of 2025. The nine months ended September 30, 2024, included $0.1 million right of use assets recognized in connection with the acquisition of M&M, and an additional $0.7 million recognized in connection with a lease amendment that was executed subsequent to the M&M acquisition for a lease that was obtained in that acquisition. Additional information about assets and liabilities obtained in business combinations can be found in “Note 2. Mergers and Acquisitions.”

Schedule of Future Undiscounted Lease Payments

Future undiscounted payments for leases with initial terms of one year or more, were as follows:


	As of September 30, 2025
(dollars in thousands)	Operating Leases		Finance Leases
Rent commitments
Remainder of 2025	$	1,618	$	123
2026	6,107		490
2027	5,623		527
2028	5,107		540
2029	4,110		540
2030	3,227		540
Thereafter	11,121		6,625
Total undiscounted cash flows	36,913		9,385
Less: Amounts representing interest	5,321		3,119
Present value of net future minimum lease payments	$	31,592	$	6,266

Schedule of Revenue Recorded in Connection with Leases

Revenues recorded in connection with these leases, reported in other income on Busey’s Consolidated Statements of Income (Unaudited), are summarized as follows:


	Three Months Ended September 30,				Nine Months Ended September 30,
(dollars in thousands)	2025		2024		2025		2024
Rental income	$	214	$	206	$	647	$	612

Schedule of Future Minimum Lease Payments

Busey is entitled to receive aggregate future lease payments as shown in the table below:


(dollars in thousands)	As of September 30, 2025
Rents to be received
Remainder of 2025	$	211
2026	738
2027	515
2028	377
2029	197
2030	117

Total lease payments from operating leases	$	2,155

DEBT SECURITIES - Schedule of Maturity of Debt Securities (Details) - USD ($) $ in Thousands	Sep. 30, 2025	Dec. 31, 2024
Amortized Cost
Due in one year or less	$ 13,055
Due after one year through five years	59,849
Due after five years through ten years	373,230
Due after ten years	1,805,597
Amortized Cost	2,251,731	$ 2,039,952
Fair Value
Due in one year or less	12,989
Due after one year through five years	57,288
Due after five years through ten years	359,557
Due after ten years	1,669,425
Fair Value	2,099,259	1,810,221
Amortized Cost
Due in one year or less	31,564
Due after one year through five years	38,433
Due after five years through ten years	14,719
Due after ten years	700,105
Amortized Cost	784,821	826,630
Fair Value
Due in one year or less	31,320
Due after one year through five years	36,972
Due after five years through ten years	13,268
Due after ten years	577,911
Fair Value	$ 659,471	$ 675,053

DERIVATIVE FINANCIAL INSTRUMENTS - Schedule of Risk Participation Agreement (Details) $ in Thousands	Sep. 30, 2025 USD ($) agreement	Dec. 31, 2024 USD ($) agreement
Risk participation agreements purchased
Derivative [Line Items]
Number of risk participation agreements \| agreement	12	5
Notional amount	$ 73,919	$ 40,092
Fair value	$ 39	$ 5
Risk participation agreements sold
Derivative [Line Items]
Number of risk participation agreements \| agreement	12	0
Notional amount	$ 106,453	$ 0
Fair value	$ 59	$ 0

CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY (Unaudited) - USD ($) $ in Thousands	Total	Cumulative effect of change in accounting principal (ASU 2023-02)	Preferred	Common stock	Additional Paid-in Capital	Retained Earnings	Retained Earnings Cumulative effect of change in accounting principal (ASU 2023-02)	AOCI	Treasury Stock
Beginning balance (in shares) at Dec. 31, 2023			0	55,244,119
Beginning balance at Dec. 31, 2023	$ 1,271,981	$ (1,391)	$ 0	$ 58	$ 1,323,595	$ 237,197	$ (1,391)	$ (218,803)	$ (70,066)
Increase (decrease) in shareholders' equity
Net income	85,586					85,586
OCI, net of tax	47,890							47,890
Stock issued in acquisition, net of stock issuance costs (in shares)				1,429,304
Stock issued in acquisition, net of stock issuance costs	34,234			$ 2	34,232
Issuance of treasury stock for ESPP (in shares)				45,679
Issuance of treasury stock for ESPP	926				(250)				1,176
Net issuance of treasury stock for RSU/PSU/DSU vesting and related tax (in shares)				153,087
Net issuance of treasury stock for RSU/PSU/DSU vesting and related tax	(1,650)				(5,592)				3,942
Net issuance of treasury stock for SSARs and options exercised net of shares redeemed and related tax (in shares)				52
Net issuance of treasury stock for SSARs and options exercised, net of shares redeemed and related tax	0				(1)				1
Cash dividends on common stock	(40,520)					(40,520)
Dividend equivalents on RSUs/PSUs/DSUs	0				1,004	(1,004)
Stock-based compensation	5,828				5,828
Ending balance (in shares) at Sep. 30, 2024			0	56,872,241
Ending balance at Sep. 30, 2024	1,402,884		$ 0	$ 60	1,358,816	279,868		(170,913)	(64,947)
Beginning balance (in shares) at Jun. 30, 2024			0	56,746,937
Beginning balance at Jun. 30, 2024	1,333,810		$ 0	$ 60	1,360,430	261,820		(220,326)	(68,174)
Increase (decrease) in shareholders' equity
Net income	32,004					32,004
OCI, net of tax	49,413							49,413
Issuance of treasury stock for ESPP (in shares)				13,109
Issuance of treasury stock for ESPP	265				(73)				338
Net issuance of treasury stock for RSU/PSU/DSU vesting and related tax (in shares)				112,143
Net issuance of treasury stock for RSU/PSU/DSU vesting and related tax	(1,254)				(4,142)				2,888
Net issuance of treasury stock for SSARs and options exercised net of shares redeemed and related tax (in shares)				52
Net issuance of treasury stock for SSARs and options exercised, net of shares redeemed and related tax	0				(1)				1
Cash dividends on common stock	(13,645)					(13,645)
Dividend equivalents on RSUs/PSUs/DSUs	0				311	(311)
Stock-based compensation	2,291				2,291
Ending balance (in shares) at Sep. 30, 2024			0	56,872,241
Ending balance at Sep. 30, 2024	1,402,884		$ 0	$ 60	1,358,816	279,868		(170,913)	(64,947)
Beginning balance (in shares) at Dec. 31, 2024			0	56,895,981
Beginning balance at Dec. 31, 2024	1,383,269		$ 0	$ 60	1,360,530	294,054		(207,039)	(64,336)
Increase (decrease) in shareholders' equity
Net income	74,512					74,512
OCI, net of tax	70,238							70,238
Stock issued in acquisition, net of stock issuance costs (in shares)			7,750	33,148,268
Stock issued in acquisition, net of stock issuance costs	808,055			$ 33	808,022
Issuance of preferred stock, net of issuance costs (in shares)			215,000
Issuance of preferred stock, net of issuance costs	207,447				207,447
Repurchase of stock (in shares)				(1,812,000)
Repurchase of stock	(40,038)								(40,038)
Issuance of treasury stock for ESPP (in shares)				79,333
Issuance of treasury stock for ESPP	1,487				(424)				1,911
Net issuance of treasury stock for RSU/PSU/DSU vesting and related tax (in shares)				446,555
Net issuance of treasury stock for RSU/PSU/DSU vesting and related tax	(4,549)				(15,256)				10,707
Net issuance of treasury stock for SSARs and options exercised net of shares redeemed and related tax (in shares)				30,906
Net issuance of treasury stock for SSARs and options exercised, net of shares redeemed and related tax	(452)				(1,174)				722
Cash dividends on preferred stock	(5,286)					(5,286)
Cash dividends on common stock	(58,973)					(58,973)
Dividend equivalents on RSUs/PSUs/DSUs	0				1,230	(1,230)
Stock-based compensation	13,125				13,125
Ending balance (in shares) at Sep. 30, 2025			222,750	88,789,043
Ending balance at Sep. 30, 2025	2,448,835		$ 0	$ 93	2,373,500	303,077		(136,801)	(91,034)
Beginning balance (in shares) at Jun. 30, 2025			222,750	89,104,678
Beginning balance at Jun. 30, 2025	2,412,546		$ 0	$ 93	2,377,560	273,799		(155,311)	(83,595)
Increase (decrease) in shareholders' equity
Net income	57,098					57,098
OCI, net of tax	18,510							18,510
Repurchase of stock (in shares)				(580,000)
Repurchase of stock	(13,547)								(13,547)
Issuance of treasury stock for ESPP (in shares)				23,232
Issuance of treasury stock for ESPP	458				(79)				537
Net issuance of treasury stock for RSU/PSU/DSU vesting and related tax (in shares)				234,401
Net issuance of treasury stock for RSU/PSU/DSU vesting and related tax	(3,002)				(8,418)				5,416
Net issuance of treasury stock for SSARs and options exercised net of shares redeemed and related tax (in shares)				6,732
Net issuance of treasury stock for SSARs and options exercised, net of shares redeemed and related tax	(88)				(243)				155
Cash dividends on preferred stock	(5,131)					(5,131)
Cash dividends on common stock	(22,307)					(22,307)
Dividend equivalents on RSUs/PSUs/DSUs	0				382	(382)
Stock-based compensation	4,298				4,298
Ending balance (in shares) at Sep. 30, 2025			222,750	88,789,043
Ending balance at Sep. 30, 2025	$ 2,448,835		$ 0	$ 93	$ 2,373,500	$ 303,077		$ (136,801)	$ (91,034)

DERIVATIVE FINANCIAL INSTRUMENTS - Schedule of Interest Rate Swaps Not Designated as Hedges (Details) - Not Designated as Hedging Instrument - USD ($) $ in Thousands	Sep. 30, 2025	Dec. 31, 2024
Interest Rate Swap
Derivative assets not designated as hedging instruments
Notional Amount	$ 1,008,584	$ 719,236
Fair Value	30,166	30,319
Derivative liabilities not designated as hedging instruments
Notional Amount	1,008,584	719,236
Fair Value	30,166	30,319
Interest rate swaps: receive-fixed, pay-floating
Derivative assets not designated as hedging instruments
Notional Amount	521,477	156,539
Fair Value	10,746	1,465
Derivative liabilities not designated as hedging instruments
Notional Amount	487,107	562,697
Fair Value	19,420	28,854
Interest rate swaps: receive-floating, pay-fixed
Derivative assets not designated as hedging instruments
Notional Amount	487,107	562,697
Fair Value	19,420	28,854
Derivative liabilities not designated as hedging instruments
Notional Amount	521,477	156,539
Fair Value	$ 10,746	$ 1,465

DEPOSITS - Schedule of Maturities of Time Deposits (Details) - USD ($) $ in Thousands	Sep. 30, 2025	Dec. 31, 2024
Time deposits by schedule of maturities
Remainder of 2025	$ 860,688
2026	1,531,369
2027	23,194
2028	10,487
2029	5,218
2030	2,409
Thereafter	423
Time deposits	$ 2,433,788	$ 1,490,635

CONSOLIDATED STATEMENTS OF CASH FLOWS (Unaudited) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2025	Sep. 30, 2024
Cash flows provided by (used in) operating activities
Net income	$ 74,512	$ 85,586
Adjustments to reconcile net income to net cash provided by (used in) operating activities:
Provision for credit losses	50,308	6,677
Amortization of intangible assets	12,182	7,586
Amortization of mortgage servicing rights	486	826
Depreciation and amortization of premises and equipment	9,505	7,186
Net amortization (accretion) on portfolio loans	(12,046)	3,602
Net amortization (accretion) of premium (discount) on investment securities	1,405	6,848
Net amortization (accretion) of premium (discount) on time deposits	(1,715)	87
Net amortization (accretion) of premium (discount) on FHLB advances and other borrowings	1,470	856
Impairment of OREO and other repossessed assets	270	0
Impairment of fixed assets held for sale	188	369
Impairment of mortgage servicing rights	35	233
Impairment of leases	28	0
Unrealized (gains) losses recognized on equity securities, net	(5,490)	(911)
(Gain) loss on sales of debt securities, net	15,549	6,817
(Gain) loss on sales of mortgage servicing rights	0	(7,724)
(Gain) loss on sales of loans, net	(1,140)	(1,307)
(Gain) loss on sales of OREO and other repossessed assets	96	(549)
(Gain) loss on sales of premises and equipment	27	(32)
(Gain) loss on life insurance proceeds	(357)	(895)
(Increase) decrease in cash surrender value of bank owned life insurance	(4,457)	(3,155)
Provision for deferred income taxes	3,132	1,905
Stock-based compensation	13,125	5,828
Proceeds from the sale of mortgage servicing rights	0	9,796
Mortgage loans originated for sale	(77,210)	(85,741)
Proceeds from sales of mortgage loans	73,098	78,006
(Increase) decrease in other assets	(1,337)	10,082
Increase (decrease) in other liabilities	(31,284)	(6,015)
Net cash provided by (used in) operating activities	120,380	125,961
Cash flows provided by (used in) investing activities
Purchases of equity securities	(919)	(647)
Purchases of debt securities available for sale	(385,411)	(31,149)
Proceeds from sales of equity securities	6,444	1,055
Proceeds from sales of debt securities available for sale	529,760	101,361
Proceeds from paydowns and maturities of debt securities held to maturity	43,409	35,932
Proceeds from paydowns and maturities of debt securities available for sale	354,041	251,175
Purchases of restricted bank stock	(35,278)	(24)
Proceeds from the redemption of restricted bank stock	11,905	884
Net (increase) decrease in loans	161,275	241,463
Net cash received in (paid for) acquisitions (see Note 2)	385,804	18,377
Cash paid for premiums on bank-owned life insurance	(46)	(74)
Proceeds from life insurance	4,334	3,092
Purchases of premises and equipment	(13,179)	(4,504)
Proceeds from disposition of premises and equipment	710	1,341
Capitalized expenditures on foreclosed real estate	(316)	0
Proceeds from sales of OREO and other repossessed assets, including cash payments collected	16,576	636
Net cash provided by (used in) investing activities	1,079,109	618,918
Cash flows provided by (used in) financing activities
Net increase (decrease) in deposits	(1,482,312)	(740,840)
Net increase (decrease) in federal funds purchased and securities sold under agreements to repurchase	(8,458)	(60,150)
Repayment of short-term borrowings	(11,158)	(36,000)
Proceeds from other borrowings, net of debt issuance costs	16,667	0
Repayment of other borrowings	(125,129)	(31,450)
Cash dividends paid	(64,259)	(40,520)
Purchase of treasury stock	(40,038)	0
Cash paid for withholding taxes on stock-based payments	(4,549)	(1,650)
Cash paid for the exercise of stock options, warrants, and SSARs	(452)	0
Issuance of treasury stock for the ESPP	1,487	0
Issuance of preferred stock, net of stock issuance costs	207,447	0
Common stock issuance costs	(920)	(141)
Net cash provided by (used in) financing activities	(1,511,674)	(910,751)
Net increase (decrease) in cash and cash equivalents	(312,185)	(165,872)
Cash and cash equivalents, beginning of period	697,659	719,581
Cash and cash equivalents, ending of period	385,474	553,709
Cash payments for:
Interest	243,489	146,302
Income taxes	16,167	12,388
Non-cash investing and financing activities:
OREO and other repossessed assets acquired in settlement of loans	$ 22,528	$ 26

OPERATING SEGMENTS AND RELATED INFORMATION - Schedule of Goodwill and Total Assets of Segments (Details) - USD ($) $ in Thousands	Sep. 30, 2025	Dec. 31, 2024
Segment Reporting Information [Line Items]
Goodwill	$ 383,323	$ 333,695
Total assets	18,188,628	12,046,722
Operating Segments \| Banking
Segment Reporting Information [Line Items]
Goodwill	360,223	310,595
Total assets	17,972,441	11,856,651
Operating Segments \| Wealth Management
Segment Reporting Information [Line Items]
Goodwill	14,108	14,108
Total assets	144,882	126,180
Operating Segments \| FirsTech
Segment Reporting Information [Line Items]
Goodwill	8,992	8,992
Total assets	45,909	57,737
Other
Segment Reporting Information [Line Items]
Goodwill	0	0
Total assets	$ 25,396	$ 6,154

- Definition

Amount of asset recognized for present right to economic benefit.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 942
-SubTopic 235
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-05(b)(1))
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Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 942
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Reference 5: http://www.xbrl.org/2003/role/disclosureRef
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Reference 6: http://www.xbrl.org/2003/role/exampleRef
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Reference 11: http://www.xbrl.org/2003/role/disclosureRef
-Topic 270
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Reference 12: http://www.xbrl.org/2003/role/disclosureRef
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-Topic 280
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 32
-Subparagraph (d)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482810/280-10-50-32

Reference 14: http://www.xbrl.org/2003/role/disclosureRef
-Topic 280
-SubTopic 10
-Name Accounting Standards Codification
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-URI https://asc.fasb.org/1943274/2147482810/280-10-50-22

Reference 15: http://www.xbrl.org/2003/role/disclosureRef
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Reference 16: http://www.xbrl.org/2003/role/disclosureRef
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Reference 17: http://www.xbrl.org/2003/role/disclosureRef
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Reference 18: http://www.xbrl.org/2003/role/disclosureRef
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Reference 19: http://www.xbrl.org/2003/role/exampleRef
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Reference 21: http://www.xbrl.org/2003/role/disclosureRef
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+ Details

- Definition

Amount, after accumulated impairment loss, of asset representing future economic benefit arising from other asset acquired in business combination or from joint venture formation or both, that is not individually identified and separately recognized.

+ References

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+ Details

DEBT SECURITIES (Tables)

9 Months Ended

Sep. 30, 2025

Investments, Debt and Equity Securities [Abstract]

Schedule of Amortized Cost, Unrealized or Unrecognized Gains and Losses and Fair Values of Securities Classified Available for Sale and Held to Maturity

The tables below provide the amortized cost, unrealized or unrecognized gains and losses, and fair values of debt securities summarized by major category:


	As of September 30, 2025
(dollars in thousands)	Amortized Cost		Unrealized				Fair Value
			Gross Gains		Gross Losses
Debt securities available for sale1

Obligations of U.S. government corporations and agencies	$	113,676	$	124	$	(195)	$	113,605
Obligations of states and political subdivisions	259,470		655		(12,581)		247,544
Asset-backed securities	285,052		510		—		285,562
Commercial mortgage-backed securities	147,183		541		(11,743)		135,981
Residential mortgage-backed securities	1,395,849		7,513		(135,786)		1,267,576
Corporate debt securities	50,501		410		(1,920)		48,991
Total debt securities available for sale	$	2,251,731	$	9,753	$	(162,225)	$	2,099,259



	Amortized Cost		Unrecognized				Fair Value
			Gross Gains		Gross Losses
Debt securities held to maturity
Commercial mortgage-backed securities	$	398,375	$	—	$	(68,743)	$	329,632
Residential mortgage-backed securities	386,446		—		(56,607)		329,839
Total debt securities held to maturity	$	784,821	$	—	$	(125,350)	$	659,471

___________________________________________

1.This table includes debt securities marked at par, with no gain or loss.


	As of December 31, 2024
(dollars in thousands)	Amortized Cost		Unrealized				Fair Value
			Gross Gains		Gross Losses
Debt securities available for sale1

Obligations of U.S. government corporations and agencies	$	1,408	$	—	$	(8)	$	1,400
Obligations of states and political subdivisions	156,534		31		(16,736)		139,829
Asset-backed securities	336,379		181		(3)		336,557
Commercial mortgage-backed securities	107,305		—		(15,131)		92,174
Residential mortgage-backed securities	1,279,090		19		(191,899)		1,087,210
Corporate debt securities	159,236		363		(6,548)		153,051
Total debt securities available for sale	$	2,039,952	$	594	$	(230,325)	$	1,810,221



	Amortized Cost		Unrecognized				Fair Value
			Gross Gains		Gross Losses
Debt securities held to maturity
Commercial mortgage-backed securities	$	415,530	$	—	$	(77,242)	$	338,288
Residential mortgage-backed securities	411,100		—		(74,335)		336,765
Total debt securities held to maturity	$	826,630	$	—	$	(151,577)	$	675,053

___________________________________________

1.This table includes debt securities marked at par, with no gain or loss.

Schedule of Maturities Of Debt Securities

All mortgage-backed securities were issued by U.S. government corporations and agencies.


	As of September 30, 2025
(dollars in thousands)	Amortized Cost		Fair Value
Debt securities available for sale
Due in one year or less	$	13,055	$	12,989
Due after one year through five years	59,849		57,288
Due after five years through ten years	373,230		359,557
Due after ten years	1,805,597		1,669,425
Debt securities available for sale	$	2,251,731	$	2,099,259

Debt securities held to maturity
Due in one year or less	$	31,564	$	31,320
Due after one year through five years	38,433		36,972
Due after five years through ten years	14,719		13,268
Due after ten years	700,105		577,911
Debt securities held to maturity	$	784,821	$	659,471

Schedule of Gains and Losses on Debt Securities Available for Sale

Realized gains and losses related to sales and calls of debt securities available for sale are summarized as follows:


	Three Months Ended September 30,				Nine Months Ended September 30,
(dollars in thousands)	2025		2024		2025		2024
Realized gains and losses on debt securities
Gross gains on debt securities	$	—	$	—	$	9	$	1
Gross (losses) on debt securities1	(13)		(11)		(15,558)		(6,818)
Realized net gains (losses) on debt securities	$	(13)	$	(11)	$	(15,549)	$	(6,817)

___________________________________________

1.During the first quarter of 2025, Busey sold available for sale debt securities with a book value of approximately $205.6 million for a pre-tax loss of $15.5 million and related estimated tax benefit of $4.1 million, as part of a balance sheet repositioning strategy. During the first quarter of 2024, Busey sold available for sale debt securities with a book value of approximately $108.2 million for a pre-tax loss of $6.8 million and related estimated tax benefit of $1.8 million, as part of a balance sheet repositioning strategy.

Schedule of Debt Securities in an Unrealized or Unrecognized Loss Position

The following information pertains to debt securities with gross unrealized or unrecognized losses, aggregated by investment category and the length of time that individual securities have been in a continuous loss position:


	As of September 30, 2025
	Less than 12 months				12 months or more				Total
(dollars in thousands)	Fair Value		Unrealized Losses		Fair Value		Unrealized Losses		Fair Value		Unrealized Losses
Debt securities available for sale

Obligations of U.S. government corporations and agencies	$	69,984	$	(195)	$	—	$	—	$	69,984	$	(195)
Obligations of states and political subdivisions	99,487		(2,375)		95,200		(10,206)		194,687		(12,581)

Commercial mortgage-backed securities	5,813		(61)		72,141		(11,682)		77,954		(11,743)
Residential mortgage-backed securities	1,427		(1)		782,258		(135,785)		783,685		(135,786)
Corporate debt securities	5,967		(18)		30,956		(1,902)		36,923		(1,920)
Debt securities available for sale with gross unrealized losses	$	182,678	$	(2,650)	$	980,555	$	(159,575)	$	1,163,233	$	(162,225)




	Fair Value		Unrecognized Losses		Fair Value		Unrecognized Losses
Debt securities held to maturity
Commercial mortgage-backed securities	$	329,632	$	(68,743)	$	329,632	$	(68,743)
Residential mortgage-backed securities	329,839		(56,607)		329,839		(56,607)
Debt securities held to maturity with gross unrecognized losses	$	659,471	$	(125,350)	$	659,471	$	(125,350)


	As of December 31, 2024
	Less than 12 months				12 months or more				Total
(dollars in thousands)	Fair Value		Unrealized Losses		Fair Value		Unrealized Losses		Fair Value		Unrealized Losses
Debt securities available for sale

Obligations of U.S. government corporations and agencies	$	—	$	—	$	1,328	$	(8)	$	1,328	$	(8)
Obligations of states and political subdivisions	11,234		(209)		119,723		(16,527)		130,957		(16,736)
Asset-backed securities	14,997		(3)		—		—		14,997		(3)
Commercial mortgage-backed securities	6,238		(42)		85,936		(15,089)		92,174		(15,131)
Residential mortgage-backed securities	152,081		(640)		930,642		(191,259)		1,082,723		(191,899)
Corporate debt securities	598		(1)		143,966		(6,547)		144,564		(6,548)
Debt securities available for sale with gross unrealized losses	$	185,148	$	(895)	$	1,281,595	$	(229,430)	$	1,466,743	$	(230,325)




	Fair Value		Unrecognized Losses		Fair Value		Unrecognized Losses
Debt securities held to maturity
Commercial mortgage-backed securities	$	338,288	$	(77,242)	$	338,288	$	(77,242)
Residential mortgage-backed securities	336,765		(74,335)		336,765		(74,335)
Debt securities held to maturity with gross unrecognized losses	$	675,053	$	(151,577)	$	675,053	$	(151,577)

Additional information about debt securities in an unrealized or unrecognized loss position is presented in the tables below:


	As of September 30, 2025
(dollars in thousands)	Available for Sale			Held to Maturity			Total
Debt securities with gross unrealized or unrecognized losses, fair value	$	1,163,233		$	659,471		$	1,822,704
Gross unrealized or unrecognized losses on debt securities	162,225			125,350			287,575
Ratio of gross unrealized or unrecognized losses to debt securities with gross unrealized or unrecognized losses	13.9		%	19.0		%	15.8		%

Count of debt securities	632			55			687
Count of debt securities in an unrealized or unrecognized loss position	428			55			483


	As of December 31, 2024
(dollars in thousands)	Available for Sale			Held to Maturity			Total
Debt securities with gross unrealized or unrecognized losses, fair value	$	1,466,743		$	675,053		$	2,141,796
Gross unrealized or unrecognized losses on debt securities	230,325			151,577			381,902
Ratio of gross unrealized or unrecognized losses to debt securities with gross unrealized or unrecognized losses	15.7		%	22.5		%	17.8		%

Count of debt securities	677			55			732
Count of debt securities in an unrealized or unrecognized loss position	586			55			641

REGULATORY CAPITAL (Tables)

9 Months Ended

Sep. 30, 2025

Banking and Thrift, Other Disclosure [Abstract]

Schedule of Regulatory Capital Requirements Applicable to Busey and Busey Bank

The following tables summarize regulatory capital requirements applicable to First Busey and its subsidiary bank:


	As of September 30, 2025
	Actual				Minimum Capital Requirement				Minimum To Be Well Capitalized
(dollars in thousands)	Amount		Ratio		Amount		Ratio		Amount		Ratio
Common equity Tier 1 capital to risk weighted assets
First Busey	$	1,907,982	12.33	%	$	696,419	4.50	%	$	1,005,938	6.50	%
Busey Bank	$	2,118,059	13.73	%	$	694,126	4.50	%	$	1,002,626	6.50	%

Tier 1 capital to risk weighted assets
First Busey	$	2,130,732	13.77	%	$	928,558	6.00	%	$	1,238,078	8.00	%
Busey Bank	$	2,118,059	13.73	%	$	925,501	6.00	%	$	1,234,002	8.00	%

Total capital to risk weighted assets
First Busey	$	2,458,553	15.89	%	$	1,238,078	8.00	%	$	1,547,597	10.00	%
Busey Bank	$	2,262,302	14.67	%	$	1,234,002	8.00	%	$	1,542,502	10.00	%

Leverage ratio of Tier 1 capital to average assets
First Busey	$	2,130,732	11.62	%	$	733,327	4.00	%	N/A		N/A
Busey Bank	$	2,118,059	11.59	%	$	731,219	4.00	%	$	914,024	5.00	%


	As of December 31, 2024
	Actual				Minimum Capital Requirement				Minimum To Be Well Capitalized
(dollars in thousands)	Amount		Ratio		Amount		Ratio		Amount		Ratio
Common equity Tier 1 capital to risk weighted assets
First Busey	$	1,237,301	14.10	%	$	394,840	4.50	%	$	570,325	6.50	%
Busey Bank	$	1,438,296	16.46	%	$	393,277	4.50	%	$	568,067	6.50	%

Tier 1 capital to risk weighted assets
First Busey	$	1,314,301	14.98	%	$	526,453	6.00	%	$	701,938	8.00	%
Busey Bank	$	1,438,296	16.46	%	$	524,369	6.00	%	$	699,159	8.00	%

Total capital to risk weighted assets
First Busey	$	1,625,943	18.53	%	$	701,938	8.00	%	$	877,422	10.00	%
Busey Bank	$	1,520,938	17.40	%	$	699,159	8.00	%	$	873,949	10.00	%

Leverage ratio of Tier 1 capital to average assets
First Busey	$	1,314,301	11.06	%	$	475,348	4.00	%	N/A		N/A
Busey Bank	$	1,438,296	12.14	%	$	473,878	4.00	%	$	592,347	5.00	%

FAIR VALUE MEASUREMENTS

9 Months Ended

Sep. 30, 2025

Fair Value Disclosures [Abstract]

FAIR VALUE MEASUREMENTS

NOTE 13. FAIR VALUE MEASUREMENTS

The fair value of an asset or liability is the price that would be received by selling that asset or paid in transferring that liability (exit price) in an orderly transaction occurring in the principal market (or most advantageous market in the absence of a principal market) for such asset or liability. ASC Topic 820 “Fair Value Measurement” establishes a fair value hierarchy for valuation inputs that gives the highest priority to quoted prices in active markets for identical assets or liabilities and the lowest priority to unobservable inputs. The fair value hierarchy is as follows:

•Level 1 Inputs—Unadjusted quoted prices in active markets for identical assets or liabilities that the Company has the ability to access at the measurement date.

•Level 2 Inputs—Inputs other than quoted prices included in Level 1 that are observable for the asset or liability, either directly or indirectly. These might include quoted prices for similar assets or liabilities in active markets, quoted prices for identical or similar assets or liabilities in markets that are not active, inputs other than quoted prices that are observable for the asset or liability (such as interest rates, volatility, prepayment speeds, credit risks, etc.) or inputs that are derived principally from or corroborated by market data by correlation or other means.

•Level 3 Inputs—Unobservable inputs for estimating the fair values of assets or liabilities that reflect the Company’s own assumptions about the assumptions that market participants would use in pricing the assets or liabilities.

A description of the valuation methodologies used for instruments measured at fair value, as well as the general classification of such instruments pursuant to the valuation hierarchy, is set forth below. These valuation methodologies were applied to Busey’s assets and liabilities that are carried at fair value.

In general, fair value estimates are based upon quoted market prices, when available. If such quoted market prices are not available, fair values are estimated utilizing independent valuation techniques that consider identical or similar securities for which significant assumptions are derived primarily from or corroborated by observable data. Valuation adjustments may be made to ensure that financial instruments are recorded at their estimated fair values. These adjustments may include amounts to reflect, among other things, counterparty credit quality and the company's creditworthiness as well as unobservable parameters. Any such valuation adjustments are applied consistently over time. While management believes Busey's valuation methodologies are appropriate and consistent with other market participants, the use of different methodologies or assumptions to estimate the fair value of certain financial instruments could result in a different estimate of fair value at the reporting date.

Financial Assets and Financial Liabilities Measured at Fair Value on a Recurring Basis

Debt Securities Available for Sale

Debt securities classified as available for sale are reported at fair value, which is estimated using Level 2 inputs. Busey obtains fair value measurements from an independent pricing service. The independent pricing service utilizes evaluated pricing models that vary by asset class and incorporate available trade, bid, and other market information. Because many fixed income securities do not trade on a daily basis, the independent pricing service applies available information to prepare evaluations, with a focus on observable market data such as benchmark curves, benchmarking of like securities, sector groupings, and matrix pricing.

The independent pricing service uses model processes, such as the Option Adjusted Spread model, to assess interest rate impact and develop prepayment scenarios. Models and processes take into account market conventions. For each asset class, a team of evaluators gathers information from market sources and integrates relevant credit information, perceived market movements, and sector news into the evaluated pricing applications and models.

Market inputs that the independent pricing service normally seeks for evaluations of securities, listed in approximate order of priority, include: benchmark yields, reported trades, broker/dealer quotes, issuer spreads, two-sided markets, benchmark securities, bids, offers, and reference data including market research publications. The independent pricing service also monitors market indicators, industry, and economic events. For certain security types, additional inputs may be used or some of the market inputs may not be applicable. Evaluators may prioritize inputs differently on any given day for any security based on market conditions, and not all inputs listed are available for use in the evaluation process for each security evaluation on a given day. Because the data utilized was observable, the securities have been classified as Level 2.

Equity Securities

Equity securities are reported at fair value, which is estimated using Level 1 or Level 2 inputs. Fair value measurements of mutual funds or stock in active markets are estimated using unadjusted quoted prices for identical assets at the measurement date and are classified as Level 1. Fair value measurements of stock that are not active use quoted prices for identical or similar assets in markets and are classified as Level 2.

Derivative Assets and Derivative Liabilities

Busey’s derivative assets and derivative liabilities are reported at fair value, which is measured using Level 2 or Level 3 inputs. Fair values of derivative assets and liabilities are estimated based on prices that are obtained from a third-party which uses observable market inputs and, with the exception of risk participation agreements, are classified as Level 2. Due to the significance of unobservable inputs, derivative assets and liabilities related to risk participation agreements are classified as Level 3.

The following tables summarize financial assets and financial liabilities measured at estimated fair value on a recurring basis:


	As of September 30, 2025
(dollars in thousands)	Level 1 Inputs		Level 2 Inputs		Level 3 Inputs		Total Fair Value
Debt securities available for sale:

Obligations of U.S. government corporations and agencies	$	—	$	113,605	$	—	$	113,605
Obligations of states and political subdivisions	—		247,544		—		247,544
Asset-backed securities	—		285,562		—		285,562
Commercial mortgage-backed securities	—		135,981		—		135,981
Residential mortgage-backed securities	—		1,267,576		—		1,267,576
Corporate debt securities	—		48,991		—		48,991
Equity securities	190		15,741		—		15,931
Derivative assets	—		33,934		39		33,973
Derivative liabilities	—		45,914		59		45,973


	As of December 31, 2024
(dollars in thousands)	Level 1 Inputs		Level 2 Inputs		Level 3 Inputs		Total Fair Value
Debt securities available for sale:

Obligations of U.S. government corporations and agencies	$	—	$	1,400	$	—	$	1,400
Obligations of states and political subdivisions	—		139,829		—		139,829
Asset-backed securities	—		336,557		—		336,557
Commercial mortgage-backed securities	—		92,174		—		92,174
Residential mortgage-backed securities	—		1,087,210		—		1,087,210
Corporate debt securities	—		153,051		—		153,051
Equity securities	5,567		10,295		—		15,862
Derivative assets	—		30,368		5		30,373
Derivative liabilities	—		58,099		—		58,099

Activity for risk participation agreements, which are financial assets measured at estimated fair value on a recurring basis using Level 3, is summarized in the table below:


		Three Months Ended September 30,				Nine Months Ended September 30,
(dollars in thousands)	Location	2025		2024		2025		2024
Beginning Balance		$	(45)	$	8	$	5	$	15
Gains (losses) recognized in earnings	Other expense	170		(5)		163		(15)

Purchases		(145)		13		(171)		16
Sales		—		—		24		—
Assumed in acquisition		—		—		(41)		—




Ending Balance		$	(20)	$	16	$	(20)	$	16

Assets and Liabilities Measured at Fair Value on a Nonrecurring Basis

Certain financial assets and financial liabilities are measured at estimated fair value on a non-recurring basis; that is, the instruments are not measured at estimated fair value on an ongoing basis but are subject to fair value adjustments in certain circumstances (for example, when there is evidence of impairment).

Loans Evaluated Individually

Busey does not record portfolio loans at estimated fair value on a recurring basis. However, periodically, a loan is evaluated individually and is reported at the estimated fair value of the underlying collateral, less estimated costs to sell, if repayment is expected solely from the collateral. If the estimated collateral value is not sufficient, a specific reserve is recorded. Collateral values are estimated using a combination of observable inputs, including recent appraisals, and unobservable inputs based on customized discounting criteria. Due to the significance of unobservable inputs, fair values of individually evaluated collateral dependent loans have been classified as Level 3.

OREO and Other Repossessed Assets

Non-financial assets measured at fair value, upon initial recognition or subsequent impairment, include OREO and other repossessed assets. OREO properties and other repossessed assets are measured using a combination of observable inputs, including recent appraisals, and unobservable inputs. Due to the significance of unobservable inputs, the estimated fair values of all OREO and other repossessed assets have been classified as Level 3.

Bank Property Held for Sale

Bank property held for sale represents certain banking center office buildings which Busey has closed and consolidated with other existing banking centers. Bank property held for sale is measured at the lower of amortized cost or estimated fair value less estimated costs to sell. Fair value estimates were based upon discounted appraisals or real estate listing prices. Due to the significance of unobservable inputs, estimated fair values of all bank property held for sale have been classified as Level 3. Bank property held for sale is included in premises and equipment, net on Busey’s Consolidated Balance Sheets (Unaudited).

The following tables summarize financial assets and financial liabilities measured at estimated fair value on a non-recurring basis:


	As of September 30, 2025
(dollars in thousands)	Level 1 Inputs		Level 2 Inputs		Level 3 Inputs		Total Fair Value
Loans evaluated individually, net of related allowance	$	—	$	—	$	19,056	$	19,056
OREO and other repossessed assets with subsequent impairment	—		—		2,628		2,628
Bank property held for sale with impairment	—		—		2,099		2,099


	As of December 31, 2024
(dollars in thousands)	Level 1 Inputs		Level 2 Inputs		Level 3 Inputs		Total Fair Value
Loans evaluated individually, net of related allowance	$	—	$	—	$	616	$	616

Bank property held for sale with impairment	—		—		2,841		2,841

The following table presents additional quantitative information about assets measured at estimated fair value on a non-recurring basis using Level 3 inputs:

As of September 30, 2025

(dollars in thousands)

Fair Value

Valuation
Techniques

Unobservable
Input

Range
(Weighted Average)

Loans evaluated individually, net of related allowance

19,056

Appraisal of collateral

Appraisal adjustments

-1.6% to -100.0%

(-32.2)%

OREO and other repossessed assets with subsequent impairment

2,628

Appraisal of collateral

Appraisal adjustments

-6.6% to -24.1%

(-7.0)%

Bank property held for sale with impairment

2,099

Appraisal of collateral or real estate listing price

Appraisal adjustments

-9.0% to -86.8%

(-57.3)%

As of December 31, 2024

(dollars in thousands)

Fair Value

Valuation
Techniques

Unobservable
Input

Range
(Weighted Average)

Loans evaluated individually, net of related allowance

616

Appraisal of collateral

Appraisal adjustments

-25.0% to -100.0%

(-74.9)%

Bank property held for sale with impairment

2,841

Appraisal of collateral or real estate listing price

Appraisal adjustments

-9.0% to -76.7%

(-51.8)%

Financial Assets and Financial Liabilities That Are Not Carried at Fair Value

Fair values of financial instruments that are not carried at fair value on Busey’s Consolidated Balance Sheets (Unaudited) were estimated as follows:


	As of September 30, 2025				As of December 31, 2024
(dollars in thousands)	Carrying Amount		Fair Value		Carrying Amount		Fair Value
Financial assets
Level 1 inputs:
Cash and cash equivalents	$	385,474	$	385,474	$	697,659	$	697,659
Level 2 inputs:
Debt securities held to maturity	784,821		659,471		826,630		675,053
Loans held for sale	8,943		8,993		3,657		3,726
Restricted bank stock	77,006		77,006		49,930		49,930
Accrued interest receivable	79,578		79,578		45,141		45,141
Level 3 inputs:
Portfolio loans, net	13,424,085		13,505,193		7,613,683		7,426,158
Mortgage servicing rights	1,441		5,260		1,304		5,627
Other servicing rights	2,274		2,315		1,482		1,591

Financial liabilities
Level 2 inputs:
Time deposits	$	2,433,788	$	2,428,428	$	1,490,635	$	1,481,591
Securities sold under agreements to repurchase	147,152		147,152		155,610		155,610

Long-term borrowings	92,431		92,452		—		—
Junior subordinated debt owed to unconsolidated trusts	77,257		71,478		74,815		67,314
Accrued interest payable	24,355		24,355		21,129		21,129
Level 3 inputs:

Subordinated notes, net of unamortized issuance costs	103,283		98,490		227,723		219,043

- Definition

The entire disclosure for the fair value of financial instruments (as defined), including financial assets and financial liabilities (collectively, as defined), and the measurements of those instruments as well as disclosures related to the fair value of non-financial assets and liabilities. Such disclosures about the financial instruments, assets, and liabilities would include: (1) the fair value of the required items together with their carrying amounts (as appropriate); (2) for items for which it is not practicable to estimate fair value, disclosure would include: (a) information pertinent to estimating fair value (including, carrying amount, effective interest rate, and maturity, and (b) the reasons why it is not practicable to estimate fair value; (3) significant concentrations of credit risk including: (a) information about the activity, region, or economic characteristics identifying a concentration, (b) the maximum amount of loss the entity is exposed to based on the gross fair value of the related item, (c) policy for requiring collateral or other security and information as to accessing such collateral or security, and (d) the nature and brief description of such collateral or security; (4) quantitative information about market risks and how such risks are managed; (5) for items measured on both a recurring and nonrecurring basis information regarding the inputs used to develop the fair value measurement; and (6) for items presented in the financial statement for which fair value measurement is elected: (a) information necessary to understand the reasons for the election, (b) discussion of the effect of fair value changes on earnings, (c) a description of [similar groups] items for which the election is made and the relation thereof to the balance sheet, the aggregate carrying value of items included in the balance sheet that are not eligible for the election; (7) all other required (as defined) and desired information.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 820
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (bbb)(1)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482106/820-10-50-2

Reference 2: http://www.xbrl.org/2003/role/exampleRef
-Topic 820
-SubTopic 10
-Name Accounting Standards Codification
-Section 55
-Paragraph 107
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482078/820-10-55-107

Reference 3: http://www.xbrl.org/2003/role/exampleRef
-Topic 820
-SubTopic 10
-Name Accounting Standards Codification
-Section 55
-Paragraph 100
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482078/820-10-55-100

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Topic 820
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (c)(3)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482106/820-10-50-2

Reference 5: http://www.xbrl.org/2003/role/disclosureRef
-Topic 820
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 6A
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482106/820-10-50-6A

Reference 6: http://www.xbrl.org/2003/role/disclosureRef
-Topic 820
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2E
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482106/820-10-50-2E

Reference 7: http://www.xbrl.org/2003/role/disclosureRef
-Topic 820
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 6A
-Subparagraph (h)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482106/820-10-50-6A

Reference 8: http://www.xbrl.org/2003/role/disclosureRef
-Topic 820
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 6A
-Subparagraph (f)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482106/820-10-50-6A

Reference 9: http://www.xbrl.org/2003/role/disclosureRef
-Topic 820
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 6A
-Subparagraph (e)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482106/820-10-50-6A

Reference 10: http://www.xbrl.org/2003/role/disclosureRef
-Topic 820
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 6A
-Subparagraph (d)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482106/820-10-50-6A

Reference 11: http://www.xbrl.org/2003/role/disclosureRef
-Topic 820
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (h)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482106/820-10-50-2

Reference 12: http://www.xbrl.org/2003/role/disclosureRef
-Topic 820
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (g)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482106/820-10-50-2

Reference 13: http://www.xbrl.org/2003/role/disclosureRef
-Topic 940
-SubTopic 820
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147478119/940-820-50-1

+ Details

PORTFOLIO LOANS - Narrative (Details) - USD ($)	3 Months Ended		9 Months Ended		12 Months Ended
PORTFOLIO LOANS - Narrative (Details) - USD ($)	Sep. 30, 2025	Sep. 30, 2024	Sep. 30, 2025	Sep. 30, 2024	Dec. 31, 2024
Accounts, Notes, Loans and Financing Receivable [Line Items]
Net deferred loan origination costs	$ 8,800,000		$ 8,800,000		$ 12,500,000
Net accretable purchase accounting adjustments			(92,000,000)		(8,800,000)
Amount of interest collected and recognized on a cash basis	0	$ 0	0	$ 0
Commitment to lend	400,000		400,000		0
Collateral dependent loans secured by real estate or business assets	39,000,000		39,000,000		$ 19,300,000
Loans in the process of foreclosure	6,100,000		6,100,000
CrossFirst
Accounts, Notes, Loans and Financing Receivable [Line Items]
PCD loans acquired and fully reserved at acquisition			35,500,000
90+ Days
Accounts, Notes, Loans and Financing Receivable [Line Items]
Gross interest income that would have been recorded if impaired loans had been current	900,000	100,000	2,100,000	600,000
Retail loans \| CRE
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans purchased	$ 0	$ 0	0	$ 6,900,000
Commercial loans \| Watch
Accounts, Notes, Loans and Financing Receivable [Line Items]
Limit above which loans are annually reviewed			2,000,000
Commercial loans \| Special Mention
Accounts, Notes, Loans and Financing Receivable [Line Items]
Limit above which loans are annually reviewed			350,000
Commercial loans \| Maximum
Accounts, Notes, Loans and Financing Receivable [Line Items]
Limit where loans are processed through an expedited underwriting process			$ 2,000,000

EARNINGS PER COMMON SHARE - Schedule of Computation of Earnings Per Common Share (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2025	Sep. 30, 2024	Sep. 30, 2025	Sep. 30, 2024
Net income per share calculations for basic and diluted methods
Net income	$ 57,098	$ 32,004	$ 74,512	$ 85,586
Dividends on preferred stock	(5,131)	0	(5,286)	0
Net income available to common stockholders	$ 51,967	$ 32,004	$ 69,226	$ 85,586
Weighted Average Shares Outstanding
Weighted average number of common shares outstanding, basic (in shares)	89,136,898	57,033,359	82,508,723	56,458,430
Weighted average number of common shares outstanding, diluted (in shares)	90,218,382	57,967,848	83,609,999	57,411,299
Basic earnings per common share (in dollars per share)	$ 0.58	$ 0.56	$ 0.84	$ 1.52
Diluted earnings per common share (in dollars per share)	$ 0.58	$ 0.55	$ 0.83	$ 1.49
Options
Weighted Average Shares Outstanding
Dilutive effect of common stock equivalents (in shares)	187	1,714	63	572
SSARs
Weighted Average Shares Outstanding
Dilutive effect of common stock equivalents (in shares)	204,106	0	191,460	0
RSU Awards
Weighted Average Shares Outstanding
Dilutive effect of common stock equivalents (in shares)	815,829	655,224	817,169	662,609
PSU Awards
Weighted Average Shares Outstanding
Dilutive effect of common stock equivalents (in shares)	32,510	254,365	65,031	264,451
DSU Awards
Weighted Average Shares Outstanding
Dilutive effect of common stock equivalents (in shares)	17,204	16,766	15,656	18,390
ESPP
Weighted Average Shares Outstanding
Dilutive effect of common stock equivalents (in shares)	11,648	6,420	11,897	6,847

PORTFOLIO LOANS - Schedule of the Financial Effect of Loan Modifications (Details)	3 Months Ended		9 Months Ended
	Sep. 30, 2025	Sep. 30, 2024	Sep. 30, 2025	Sep. 30, 2024
Loans identified as impaired
Weighted Average Interest Rate Reduction	5.00%		5.00%
Weighted Average Term Extension	6 months	5 months	11 months	10 months
Commercial loans \| C&I and other commercial
Loans identified as impaired
Weighted Average Interest Rate Reduction	5.00%		5.00%
Weighted Average Term Extension	6 months	6 months	10 months	1 year 2 months 12 days
Commercial loans \| CRE & Retail real estate
Loans identified as impaired
Weighted Average Interest Rate Reduction	0.00%		0.00%
Weighted Average Term Extension	8 months	4 months	1 year 3 months 18 days	4 months
Commercial loans \| Real estate construction
Loans identified as impaired
Weighted Average Interest Rate Reduction	0.00%		0.00%
Weighted Average Term Extension		6 months	1 year 3 months 18 days	6 months

STOCK-BASED COMPENSATION - CrossFirst Acquisition (Details) - shares	Mar. 01, 2025	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
PSU Awards \| CrossFirst Acquisition
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Target level of performance percentage		75.00%	100.00%
TSR PSU Awards \| CrossFirst Acquisition
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Target level of performance percentage		76.90%	96.20%	94.50%
SSARs \| CrossFirst \| Common \| CrossFirst
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Shares received for each share owned (in shares)	0.6675

OUTSTANDING COMMITMENTS AND CONTINGENT LIABILITIES - Schedule of Contractual Amount of Exposure to Off-Balance-Sheet Risk (Details) - USD ($) $ in Thousands	Sep. 30, 2025	Dec. 31, 2024
Credit Commitments and Contingencies
Total commitments	$ 4,898,745	$ 2,548,178
Commitments to extend credit
Credit Commitments and Contingencies
Total commitments	4,766,360	2,512,714
Standby letters of credit
Credit Commitments and Contingencies
Total commitments	$ 132,385	$ 35,464

FAIR VALUE MEASUREMENTS - Schedule of Assets and Liabilities Measured at Fair Value on a Non-Recurring Basis (Details) - Fair Value, Nonrecurring - USD ($) $ in Thousands	Sep. 30, 2025	Dec. 31, 2024
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loans evaluated individually, net of related allowance	$ 19,056	$ 616
Bank property held for sale with impairment	2,099	2,841
OREO and other repossessed assets with subsequent impairment
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
OREO and other repossessed assets with subsequent impairment	2,628
Level 1 Inputs
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loans evaluated individually, net of related allowance	0	0
Bank property held for sale with impairment	0	0
Level 1 Inputs \| OREO and other repossessed assets with subsequent impairment
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
OREO and other repossessed assets with subsequent impairment	0
Level 2 Inputs
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loans evaluated individually, net of related allowance	0	0
Bank property held for sale with impairment	0	0
Level 2 Inputs \| OREO and other repossessed assets with subsequent impairment
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
OREO and other repossessed assets with subsequent impairment	0
Level 3 Inputs
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Loans evaluated individually, net of related allowance	19,056	616
Bank property held for sale with impairment	2,099	$ 2,841
Level 3 Inputs \| OREO and other repossessed assets with subsequent impairment
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
OREO and other repossessed assets with subsequent impairment	$ 2,628

BORROWINGS

9 Months Ended

Sep. 30, 2025

Debt Disclosure [Abstract]

BORROWINGS

NOTE 7. BORROWINGS

Securities Sold Under Agreements to Repurchase

Securities sold under agreements to repurchase, which are classified as secured borrowings, generally mature daily. Securities sold under agreements to repurchase are reflected at the amount of cash received in connection with the transaction. The underlying securities are held by Busey’s safekeeping agent. Busey may be required to provide additional collateral based on fluctuations in the fair value of the underlying securities. Securities sold under agreements to repurchase were as follows:


	As of
(dollars in thousands)	September 30, 2025			December 31, 2024
Securities sold under agreements to repurchase	$	147,152		$	155,610
Weighted average rate for securities sold under agreements to repurchase	2.50		%	2.63		%

Revolving Line of Credit

On May 28, 2021, Busey entered into a Second Amended and Restated Credit Agreement, pursuant to which Busey has access to a $40.0 million revolving line of credit bearing an interest rate of 1.80% plus the one-month forward-looking term rate based on SOFR. After executing subsequent amendments, the current termination date for the revolving line of credit is April 30, 2026. As of September 30, 2025, there was no balance outstanding on the revolving line of credit. The revolving line of credit incurs an insignificant non-usage fee based on any undrawn amounts.

Short-term Borrowings

Busey had no short term borrowings as of either September 30, 2025, or December 31, 2024. When applicable, Busey’s short-term borrowings include loans maturing within one year of the loan origination date, the current portion of long-term debt that is due within 12 months, and federal funds purchased. Federal funds purchased are short-term borrowings that generally mature between one day and 90 days. During the second quarter of 2025, Busey purchased federal funds to test operational availability to access funds if needed.

Long-term Borrowings

Busey’s long-term borrowings consist of borrowings maturing more than one year from the loan origination date, excluding the current portion that is due within 12 months, and finance lease liabilities. Long-term borrowings are presented in the table below:


	As of
(dollars in thousands)	September 30, 2025		December 31, 2024
Long-term borrowings

FHLB borrowings	$	79,174	$	—
Secured borrowings	6,991		—

Finance lease liabilities	6,266		—
Total long-term borrowings	$	92,431	$	—

Funds borrowed from the FHLB, listed above, consisted of twelve notes with a weighted average interest rate of 2.22% and a weighted average maturity period of 2.30 years as of September 30, 2025. Maturity dates for the long-term FHLB borrowings range from August 2027 through October 2028.

Acquired SBA loans that did not qualify for sale accounting treatment are presented as secured borrowings. Secured borrowings consisted of nine notes with a weighted average maturity period of 17.49 years as of September 30, 2025. Maturity dates for the secured borrowings range from September 2030 to March 2046.

Subordinated Notes

On June 1, 2020, Busey issued $125.0 million of fixed-to-floating rate subordinated notes scheduled to mature on June 1, 2030. The subordinated notes, which qualified as Tier 2 capital for regulatory purposes, bore interest at an annual rate of 5.25% for the first five years after issuance. Thereafter, the notes were to bear interest at a floating rate equal to a three-month benchmark rate plus a spread of 5.11%, as calculated on each applicable determination date. The subordinated notes, which were unsecured obligations of the Company, had an optional redemption, in whole or in part, on any interest payment date on or after June 1, 2025. On June 1, 2025, Busey redeemed the entire $125.0 million outstanding principal amount of the subordinated notes.

On June 2, 2022, Busey issued $100.0 million aggregate principal amount of 5.000% fixed-to-floating rate subordinated notes maturing June 15, 2032, which qualify as Tier 2 capital for regulatory purposes. The price to the public for the subordinated notes was 100% of the principal amount of the subordinated notes. Interest on the subordinated notes accrues at a rate equal to (1) 5.000% per annum from the original issue date to, but excluding, June 15, 2027, payable semiannually in arrears, and (2) a floating rate per annum equal to a benchmark rate, which is the Three-Month Term SOFR (as defined in the subordinated notes), plus a spread of 252 bps from and including June 15, 2027, payable quarterly in arrears. The subordinated notes have an optional redemption, in whole or in part, on any interest payment date on or after June 15, 2027.

Associated with the M&M acquisition completed on April 1, 2024 (see “Note 2. Mergers and Acquisitions”), Busey acquired a $4.0 million 5.25% fixed-to-floating rate subordinated note maturing December 4, 2030, which qualified as Tier 2 capital for regulatory purposes. Interest on the subordinated note accrues at a rate equal to (1) 5.25% per annum from the original issue date to December 4, 2025, and (2) a floating rate per annum equal to a benchmark rate, which is the Three-Month Term SOFR (as defined in the subordinated notes), plus a spread of 497 bps from December 4, 2025. At September 30, 2025, there was an immaterial amount of fair value discount outstanding, to be accreted through the earliest optional redemption date. The subordinated note has an optional redemption, in whole or in part, on or after December 4, 2025. Subsequent to quarter end, on October 24, 2025, Busey issued a conditional notice of full redemption of this subordinated note. The redemption of the subordinated note is subject to and conditioned upon regulatory approval from the Federal Reserve. Assuming the requisite approvals are obtained, the subordinated note will be redeemed on its optional redemption date of December 4, 2025.

Unamortized debt issuance costs related to Busey’s subordinated notes are presented in the following table:


	As of
(dollars in thousands)	September 30, 2025		December 31, 2024
Unamortized debt issuance costs
Subordinated notes issued in 2020	$	—	$	222
Subordinated notes issued in 2022	707		1,004
Total unamortized debt issuance costs	$	707	$	1,226

- Definition

The entire disclosure for information about short-term and long-term debt arrangements, which includes amounts of borrowings under each line of credit, note payable, commercial paper issue, bonds indenture, debenture issue, own-share lending arrangements and any other contractual agreement to repay funds, and about the underlying arrangements, rationale for a classification as long-term, including repayment terms, interest rates, collateral provided, restrictions on use of assets and activities, whether or not in compliance with debt covenants, and other matters important to users of the financial statements, such as the effects of refinancing and noncompliance with debt covenants.

+ References

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Reference 13: http://www.xbrl.org/2003/role/disclosureRef
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Reference 14: http://www.xbrl.org/2003/role/disclosureRef
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+ Details

Insider Trading Arrangements	3 Months Ended
Insider Trading Arrangements	Sep. 30, 2025 shares
Trading Arrangements, by Individual
Non-Rule 10b5-1 Arrangement Adopted	false
Rule 10b5-1 Arrangement Terminated	false
Non-Rule 10b5-1 Arrangement Terminated	false
Michael David Cassens [Member]
Trading Arrangements, by Individual
Material Terms of Trading Arrangement	On August 15, 2025, Michael David Cassens, a member of Busey’s Board of Directors, adopted a Rule 10b5‑1 trading arrangement that is intended to satisfy the affirmative defense conditions of Rule 10b5‑1(c) of the Exchange Act (the “Cassens Trading Plan”). The Cassens Trading Plan provides for the sale of up to 31,702 shares of Busey common stock in several transactions pursuant to one or more market or limit orders. The plan will cease upon the earlier of August 15, 2027, or the sale of all shares subject to the Cassens Trading Plan.
Name	Michael David Cassens
Title	member of Busey’s Board of Directors
Rule 10b5-1 Arrangement Adopted	true
Adoption Date	August 15, 2025
Expiration Date	August 15, 2027
Arrangement Duration	730 days
Aggregate Available	31,702

OPERATING SEGMENTS AND RELATED INFORMATION (Tables)

9 Months Ended

Sep. 30, 2025

Segment Reporting [Abstract]

Schedule of Information Relating to Operating Segments

Goodwill and total assets are summarized below by operating segment. The “other” category included in the tables below consists of the parent company and the elimination of intercompany transactions:


	As of September 30, 2025
(dollars in thousands)	Banking		Wealth Management		FirsTech		Other		Total
Goodwill	$	360,223	$	14,108	$	8,992	$	—	$	383,323
Total assets	17,972,441		144,882		45,909		25,396		18,188,628


	As of December 31, 2024
(dollars in thousands)	Banking		Wealth Management		FirsTech		Other		Total
Goodwill	$	310,595	$	14,108	$	8,992	$	—	$	333,695
Total assets	11,856,651		126,180		57,737		6,154		12,046,722

Financial results by operating segment, including significant expense categories provided to the chief operating decision maker, are summarized below:


	Three Months Ended September 30, 2025
(dollars in thousands)	Banking		Wealth Management		FirsTech		Other		Total
Interest income	$	244,504	$	—	$	—	$	1	$	244,505
Intersegment interest income	—		—		16		(16)		—
Interest expense	86,524		—		—		2,844		89,368
Intersegment interest expense	951		—		—		(951)		—
Net interest income	157,029		—		16		(1,908)		155,137
Provision for credit losses	(985)		—		—		—		(985)
Net interest income after provision for credit losses	158,014		—		16		(1,908)		156,122

Noninterest income
Wealth management fees	—		17,184		—		—		17,184
Payment technology solutions	—		—		5,092		—		5,092
Treasury management services	4,598		—		—		—		4,598
Card services and ATM fees	4,799		—		—		—		4,799
Other service charges on deposit accounts	1,617		—		—		—		1,617
All other noninterest income	5,957		183		(4)		1,772		7,908
Intersegment noninterest income	564		—		443		(1,007)		—
Noninterest income	17,535		17,367		5,531		765		41,198

Revenue	174,564		17,367		5,547		(1,143)		196,335

Noninterest expense
Salaries, wages, and employee benefits	53,264		7,576		2,620		10,685		74,145
Data processing	8,062		658		931		63		9,714
Amortization of intangible assets	4,292		215		—		—		4,507
Interchange expense	—		—		1,336		—		1,336
All other noninterest expense	26,706		562		674		2,374		30,316
Intersegment noninterest expense	4,346		885		404		(5,635)		—
Noninterest expense	96,670		9,896		5,965		7,487		120,018

Income (loss) before income taxes	78,879		7,471		(418)		(8,630)		77,302
Income taxes	21,283		1,793		(112)		(2,760)		20,204
Net income	$	57,596	$	5,678	$	(306)	$	(5,870)	$	57,098


	Three Months Ended September 30, 2024
(dollars in thousands)	Banking		Wealth Management		FirsTech		Other		Total
Interest income	$	134,598	$	—	$	—	$	8	$	134,606
Intersegment interest income	—		—		12		(12)		—
Interest expense	47,611		—		—		4,348		51,959
Intersegment interest expense	457		—		—		(457)		—
Net interest income	86,530		—		12		(3,895)		82,647
Provision for credit losses	409		—		—		—		409
Net interest income after provision for credit losses	86,121		—		12		(3,895)		82,238

Noninterest income
Wealth management fees	—		15,378		—		—		15,378
Payment technology solutions	—		—		5,265		—		5,265
Treasury management services	2,201		—		—		—		2,201
Card services and ATM fees	3,557		—		—		—		3,557
Other service charges on deposit accounts	2,390		—		—		—		2,390
All other noninterest income	5,431		791		(1)		833		7,054
Intersegment noninterest income	372		—		286		(658)		—
Noninterest income	13,951		16,169		5,550		175		35,845

Revenue	100,481		16,169		5,562		(3,720)		118,492

Noninterest expense
Salaries, wages, and employee benefits	29,615		6,606		2,357		6,015		44,593
Data processing	5,298		544		938		130		6,910
Amortization of intangible assets	2,268		280		—		—		2,548
Interchange expense	—		—		1,352		—		1,352
All other noninterest expense	16,273		573		639		2,631		20,116
Intersegment noninterest expense	2,879		774		361		(4,014)		—
Noninterest expense	56,333		8,777		5,647		4,762		75,519

Income (loss) before income taxes	43,739		7,392		(85)		(8,482)		42,564
Income taxes	10,518		1,774		(24)		(1,708)		10,560
Net income	$	33,221	$	5,618	$	(61)	$	(6,774)	$	32,004


	Nine Months Ended September 30, 2025
(dollars in thousands)	Banking		Wealth Management		FirsTech		Other		Total
Interest income	$	658,760	$	—	$	—	$	6	$	658,766
Intersegment interest income	—		—		46		(46)		—
Interest expense	235,288		—		—		11,427		246,715
Intersegment interest expense	2,308		—		—		(2,308)		—
Net interest income	421,164		—		46		(9,159)		412,051
Provision for credit losses	50,308		—		—		—		50,308
Net interest income after provision for credit losses	370,856		—		46		(9,159)		361,743

Noninterest income
Wealth management fees	—		51,325		—		—		51,325
Payment technology solutions	—		—		15,121		—		15,121
Treasury management services	12,596		—		—		—		12,596
Card services and ATM fees	13,388		—		—		—		13,388
Other service charges on deposit accounts	4,663		—		—		—		4,663
All other noninterest income	2,134		594		(6)		7,469		10,191
Intersegment noninterest income	1,232		—		1,217		(2,449)		—
Noninterest income	34,013		51,919		16,332		5,020		107,284

Revenue	455,177		51,919		16,378		(4,139)		519,335

Noninterest expense
Salaries, wages, and employee benefits	157,237		21,713		7,952		33,166		220,068
Data processing	28,392		1,873		2,790		255		33,310
Amortization of intangible assets	11,497		685		—		—		12,182
Interchange expense	—		—		3,976		—		3,976
All other noninterest expense	72,693		1,889		2,009		13,754		90,345
Intersegment noninterest expense	14,167		2,443		1,133		(17,743)		—
Noninterest expense	283,986		28,603		17,860		29,432		359,881

Income (loss) before income taxes	120,883		23,316		(1,482)		(33,571)		109,146
Income taxes	37,142		5,596		(393)		(7,711)		34,634
Net income	$	83,741	$	17,720	$	(1,089)	$	(25,860)	$	74,512


	Nine Months Ended September 30, 2024
(dollars in thousands)	Banking		Wealth Management		FirsTech		Other		Total
Interest income	$	392,336	$	—	$	—	$	29	$	392,365
Intersegment interest income	324		—		37		(361)		—
Interest expense	138,060		—		—		13,272		151,332
Intersegment interest expense	2,109		—		—		(2,109)		—
Net interest income	252,491		—		37		(11,495)		241,033
Provision for credit losses	6,677		—		—		—		6,677
Net interest income after provision for credit losses	245,814		—		37		(11,495)		234,356

Noninterest income
Wealth management fees	—		46,844		—		—		46,844
Payment technology solutions	—		—		16,889		—		16,889
Treasury management services	6,247		—		—		—		6,247
Card services and ATM fees	9,947		—		—		—		9,947
Other service charges on deposit accounts	7,059		—		—		—		7,059
All other noninterest income	15,414		1,145		(1)		917		17,475
Intersegment noninterest income	1,004		—		812		(1,816)		—
Noninterest income	39,671		47,989		17,700		(899)		104,461

Revenue	292,162		47,989		17,737		(12,394)		345,494

Noninterest expense
Salaries, wages, and employee benefits	87,358		19,831		7,277		15,695		130,161
Data processing	15,742		1,591		2,790		437		20,560
Amortization of intangible assets	6,705		881		—		—		7,586
Interchange expense	—		—		4,696		—		4,696
All other noninterest expense	49,954		2,079		1,822		6,014		59,869
Intersegment noninterest expense	8,605		2,322		1,081		(12,008)		—
Noninterest expense	168,364		26,704		17,666		10,138		222,872

Income (loss) before income taxes	117,121		21,285		71		(22,532)		115,945
Income taxes	30,711		5,108		18		(5,478)		30,359
Net income	$	86,410	$	16,177	$	53	$	(17,054)	$	85,586

SIGNIFICANT ACCOUNTING POLICIES (Policies)	9 Months Ended
SIGNIFICANT ACCOUNTING POLICIES (Policies)	Sep. 30, 2025
Accounting Policies [Abstract]
Nature of Operations	Nature of Operations First Busey Corporation, a Nevada corporation organized in 1980, is an $18.19 billion financial holding company headquartered in Leawood, Kansas. Busey’s common stock is traded on The Nasdaq Global Select Market under the symbol “BUSE” and Busey’s depositary shares, each representing a 1/40th interest in a share of Busey Series B Preferred Stock, are traded under the symbol “BUSEP.” Busey operates and reports its business in three segments: Banking, Wealth Management, and FirsTech. •The Banking operating segment provides a full range of banking services to individual and corporate customers through its banking center network in Arizona, Colorado, Florida, Illinois, Indiana, Kansas, Missouri, New Mexico, Oklahoma, and Texas. •The Wealth Management operating segment provides a full range of asset management, investment, brokerage, fiduciary, philanthropic advisory, tax preparation, and farm management services to individuals, businesses, and foundations. •The FirsTech operating segment provides comprehensive and innovative payment technology solutions including online, mobile, and voice-recognition bill payments; money management and credit card networks; direct debit services; lockbox remittance processing for payments made by mail; and walk-in payments. FirsTech also provides additional tools to help clients with billing, reconciliation, bill reminders, and treasury services. For additional information about Busey's operating segments, see “Note 16. Operating Segments and Related Information.” Busey conducts its Banking and Wealth Management services through Busey Bank, and provides payment technology solutions through Busey Bank’s wholly owned subsidiary, FirsTech. Busey also has various other subsidiaries that are not significant to the consolidated entity.
Basis of Financial Statement Presentation	Basis of Financial Statement Presentation These unaudited consolidated financial statements and related notes should be read together with the audited consolidated financial statements included in Busey's 2024 Annual Report. These interim unaudited consolidated financial statements serve to update Busey’s 2024 Annual Report and may not include all information and notes necessary to constitute a complete set of financial statements. Busey’s unaudited consolidated financial statements are prepared in conformity with GAAP, and reflect the elimination of intercompany accounts and transactions. Certain prior year amounts have been reclassified to conform to the current period presentation. These reclassifications did not have a material impact on Busey’s consolidated financial condition or results of operations. In the opinion of Busey’s management, the unaudited consolidated financial statements reflect all normal, recurring adjustments needed to present fairly Busey’s results for the interim periods. The results of operations for interim periods are not necessarily indicative of the results that may be expected for the full year or any other interim period.
Use of Estimates	Use of Estimates In preparing the accompanying unaudited consolidated financial statements in conformity with GAAP, Busey’s management is required to make estimates and assumptions that affect the amounts reported in the financial statements and the disclosures provided. Actual results could differ from those estimates. Critical accounting estimates which are particularly susceptible to significant change in the near term relate to the fair value of assets acquired and liabilities assumed in business combinations, goodwill, income taxes, and the determination of the ACL.
Cash and Cash Equivalents	Cash and Cash Equivalents Cash and cash equivalents include cash on hand, cash items in process of collection, amounts due from other banks, and interest-bearing deposits held with other financial institutions. The carrying amount of these instruments is considered a reasonable estimate of fair value.
Finance Leases	A determination is made at inception if an arrangement contains a lease. For arrangements containing leases, Busey classifies the lease as either operating, finance, or short-term. Busey recognizes operating and finance leases as right of use assets and corresponding lease liabilities. Right of use assets are recognized on the lease commencement date at amounts equal to the respective lease liabilities, adjusted for prepaid lease payments, initial direct costs, and lease incentives received. Lease liabilities are recognized at the present value of the remaining contractual fixed lease payments, discounted using the rate implicit in the lease or Busey’s incremental borrowing rate. ASC Topic 842 “Leases” requires the use of the rate implicit in the lease whenever this rate is readily determinable. If not readily determinable, Busey uses its incremental borrowing rate at lease inception, on a collateralized basis, over a similar term. For operating leases existing prior to Busey’s adoption of ASC Topic 842 on January 1, 2019, Busey used a borrowing rate that corresponded to the lease term remaining as of the date of adoption of ASC Topic 842. Busey’s lease agreements often include one or more options to renew at Busey’s discretion. When Busey considers the exercise of a renewal option to be reasonably certain, contractual fixed lease payments for the renewal term are included in the calculation of the right of use asset and lease liability. Right of use assets are reviewed for impairment in accordance with Busey’s policies regarding long-lived assets. Operating Leases Right of use assets for operating leases are included in other assets on the Consolidated Balance Sheets (Unaudited). Lease liabilities for operating leases are included in other liabilities on the Consolidated Balance Sheets (Unaudited). Lease costs for operating leases are recognized on a straight-line basis over the lease term. Lease costs are reflected as noninterest expense for net occupancy of premises or for furniture and equipment expenses, as appropriate, on the Consolidated Statements of Income (Unaudited). Variable lease payments are expensed as incurred. Finance Leases Right of use assets for finance leases and the related accumulated amortization are included in premises and equipment, net, on the Consolidated Balance Sheets (Unaudited). Lease liabilities for finance leases are included in long-term borrowings on the Consolidated Balance Sheets (Unaudited). Repayments of the principal portion of finance lease liabilities are reflected as financing activities on the Consolidated Statements of Cash Flows (Unaudited). Lease costs for finance leases are composed of interest expense and amortization expense. Interest expense on finance leases is reflected as interest expense on long-term borrowings on the Consolidated Statements of Income (Unaudited). Amortization expense on finance leases is reflected as noninterest expense for net occupancy of premises on the Consolidated Statements of Income (Unaudited). Busey had one finance lease as of September 30, 2025, which was acquired through its acquisition of CrossFirst. Short-term Leases Leases with terms of twelve months or less are classified as short-term leases. Busey made an accounting policy election to not recognize short-term leases on the balance sheet. Lease costs for short-term leases are reflected as noninterest expense for net occupancy of premises or for furniture and equipment expenses, as appropriate, on the Consolidated Statements of Income (Unaudited). For additional information about Busey’s leases, see “Note 5. Leases.”
Income Taxes	Income Taxes Busey is subject to income taxes in U.S. federal and various state jurisdictions. First Busey Corporation and its subsidiaries file consolidated federal and state income tax returns with each subsidiary computing its taxes on a separate entity basis. Tax regulations within each jurisdiction are subject to the interpretation of the related tax laws and regulations, which requires significant judgment. On July 4, 2025, new federal tax legislation commonly referred to as the “One Big Beautiful Bill Act” (the “OBBBA”) was enacted, which made permanent many of the tax provisions of the 2017 Tax Cuts and Jobs Act that were set to expire in 2025 and introduced several significant amendments to federal tax legislation. Key provisions of the OBBBA include the restoration of immediate expensing of domestic research and development expenditures, reinstatement of 100% bonus depreciation, more favorable rules for determining the limitation on business interest expense, and incentives for financial institutions to increase lending in rural and agricultural communities. The effects of the legislation were reflected in the unaudited consolidated financial statements for the period ending September 30, 2025, and did not have a material impact on our results of operations. Busey will continue evaluating the impact of this legislation for future reporting periods. As of September 30, 2025, Busey Bank was under examination by the Florida Department of Revenue for its 2020 to 2022 corporate income tax filings. Busey Bank accrued $0.1 million related to potential assessment adjustments and interest. Busey had no accruals for payments of interest and penalties related to uncertain tax positions at September 30, 2025 or 2024. As of September 30, 2025, Busey was also under examination by the Illinois Department of Revenue for M&M’s tax filings for the tax years ended December 31, 2022 and 2023.
Impact of Recently Adopted Accounting Standards and Recently Issued Accounting Standards Not Yet Adopted	Impact of Recently Adopted Accounting Standards In March 2024, the FASB issued ASU 2024-01 “Compensation-Stock Compensation (Topic 718): Scope Application of Profits Interest and Similar Awards” to clarify that certain “profits interests” are within the scope of Topic 718 by amending the language and providing illustrative examples on how the scope guidance in paragraph 718-10-15-3 should be applied. This update is intended to improve clarity of the accounting standards codification, not to change the guidance. This update was adopted on a prospective basis for annual and interim reporting periods beginning January 1, 2025. Busey does not currently have any Profit Interest and Similar Awards, so adoption of this ASU did not have any impact on its financial position or results of operations. In November 2023, the FASB issued ASU 2023‑07 “Segment Reporting (Topic 820): Improvements to Reportable Segment Disclosures” requiring enhanced disclosures related to significant segment expenses. This standard was adopted on a retrospective basis beginning with the annual reporting period ending December 31, 2024, and for interim reporting periods within fiscal years starting January 1, 2025. Adoption of this standard did not have a material impact on Busey’s financial position or results of operations, but resulted in enhanced disclosures. Recently Issued Accounting Standards Not Yet Adopted In September 2025, the FASB issued ASU 2025-07 “Derivatives and Hedging (Topic 815) and Revenue from Contracts with Customers (Topic 606): Derivatives Scope Refinements and Scope Clarification for Share-Based Noncash Consideration from a Customer in a Revenue Contract,” to reduce diversity in the application of derivative accounting practices. This update provides a scope limitation on the definition of a derivative subject to derivative accounting under ASC Topic 815, Derivatives and Hedging, to exclude certain non-exchange-traded contracts with contingencies based on operations or activities specific to one of the parties to the contract. In addition, this update clarifies that share-based noncash consideration from a customer that is contingent on the satisfaction of performance obligations should not be recognized at contract inception as a derivative asset or an equity security, but rather should be accounted for under the guidance in ASC Topic 606, Revenue from Contracts with Customers, and that guidance in other topics does not apply to share-based noncash consideration from a customer for the transfer of goods or services unless or until the entity’s right to receive or retain the share-based noncash consideration is unconditional under ASC Topic 606. The amendments in this update may be applied on either a prospective or modified retrospective basis, and will be effective for Busey for annual and interim reporting periods beginning January 1, 2027. Early adoption is permitted. Busey is currently evaluating the effect this ASU may have on its financial position and results of operations. In September 2025, the FASB issued ASU 2025-06 “Intangibles—Goodwill and Other—Internal-Use Software (Subtopic 350-40): Targeted Improvements to the Accounting for Internal-Use Software,” changing the criteria for capitalizing software costs to the following: (1) a commitment has been made to fund the software project, and (2) it is probable the project will be competed and used to perform its intended function. Under this update, software development stages are no longer a consideration in the determination of which costs are capitalized. The amendments in this update may be adopted on a prospective, modified transition, or retrospective basis, and will be effective for Busey for annual and interim reporting periods beginning January 1, 2028. Early adoption is permitted. Busey is currently evaluating the effect this ASU may have on its financial position and results of operations. In July 2025, the FASB issued ASU 2025-05 “Financial Instruments—Credit Losses (Topic 326): Measurement of Credit Losses for Accounts Receivable and Contract Assets,” providing a practical expedient which, if elected, permits an entity to assume that current conditions as of the balance sheet date will remain static for the remaining life of the assets, removing the requirement to consider reasonable, supportable forecasts. The amendments in this update are to be applied prospectively, and will be effective for Busey for annual and interim reporting periods beginning January 1, 2026. Early adoption is permitted. Busey is currently evaluating the effect this ASU may have on its financial position and results of operations. In November 2024, the FASB issued ASU 2024-04 “Debt—Debt with Conversion and Other Options (Subtopic 470-20): Induced Conversions of Convertible Debt Instruments” to clarify when certain settlements of convertible debt instruments should be accounted for as an induced conversion. The amendments in this update may be applied on either a prospective or retrospective basis and will be effective for Busey for annual and interim reporting periods beginning January 1, 2026. Because Busey does not currently have any convertible debt, the Company does not expect adoption of this ASU to have any impact on its financial position or results of operations. In November 2024, the FASB issued ASU 2024-03 “Income Statement—Reporting Comprehensive Income—Expense Disaggregation Disclosures (Subtopic 220-40): Disaggregation of Income Statement Expenses” to require additional disclosures within the notes to the financial statements about certain expense items. Specifically, disaggregation of income statement captions that contain expenses within the following five categories is required: (1) purchases of inventory, (2) employee compensation, (3) depreciation, (4) intangible asset amortization, and (5) depreciation, depletion, and amortization (“DD&A”) costs recognized as part of oil- and gas-producing activities or other amounts of depletion expense. Further, this update requires disclosure of the total amount of selling expenses and the entity’s definition of selling expenses. This update provides a practical expedient for banks and bank holding companies to continue presenting salaries and employee benefits in conformity with SEC Rule 210.9-04 instead of requiring those entities to apply the employee compensation definition included in Subtopic 220-40. The amendments in this update may be applied on either a prospective or retrospective basis and will be effective for Busey beginning with the annual reporting period ending December 31, 2027, and interim reporting periods beginning January 1, 2028. Early adoption is permitted. Because this update relates only to disclosure, Busey does not expect adoption of this ASU to have any impact on its financial position or results of operations. In December 2023, the FASB issued ASU 2023‑09 “Income Taxes (Topic 740): Improvements to Income Tax Disclosures,” which requires more detailed disclosures of income taxes paid net of refunds received, income from continuing operations before income tax expense or benefit, and income tax expense from continuing operations. This standard is to be applied on a prospective basis, with retrospective application permitted, and will be effective for Busey for annual reporting periods beginning with the fiscal year ending December 31, 2025. Busey does not expect adoption of this ASU to have a material impact on its financial position or results of operations. In October 2023, the FASB issued ASU 2023‑06 “Disclosure Improvements: Codification Amendments in Response to the SEC’s Disclosure Update and Simplification Initiative” which aligns certain GAAP disclosure requirements with the SEC’s disclosure requirements, in order to better facilitate comparisons between entities that are subject to the SEC’s existing disclosures with entities that were not previously subject to the SEC’s requirements. Amendments in this update should be applied prospectively, and the effective date for Busey for each amendment in this ASU will be the date on which the SEC removes the related disclosure from Regulation S‑X or Regulation S‑K. Early adoption is prohibited. If the SEC has not removed the related disclosures from Regulation S‑X or Regulation S‑K by June 30, 2027, the pending content of this update will be removed from the ASC and will not become effective for any entity. Busey does not expect adoption of this ASU to have a material impact on its financial position or results of operations.
Subsequent Events	Subsequent Events Busey has evaluated subsequent events for potential recognition and/or disclosure through the date the unaudited consolidated financial statements included in this Quarterly Report were issued. Subsequent to quarter end, on October 24, 2025, Busey issued a conditional notice of full redemption of its $4.0 million 5.25% Subordinated Note maturing December 4, 2030, which was acquired on April 1, 2024, in connection with the acquisition of M&M. The redemption of the Subordinated Note is subject to and conditioned upon regulatory approval from the Federal Reserve. Assuming the requisite approvals are obtained, the Subordinated Note will be redeemed on its optional redemption date of December 4, 2025. Other than this event, there were no significant events subsequent to the quarter ended September 30, 2025, through the filing date of these unaudited consolidated financial statements.
Fair Value Measurements	NOTE 13. FAIR VALUE MEASUREMENTS The fair value of an asset or liability is the price that would be received by selling that asset or paid in transferring that liability (exit price) in an orderly transaction occurring in the principal market (or most advantageous market in the absence of a principal market) for such asset or liability. ASC Topic 820 “Fair Value Measurement” establishes a fair value hierarchy for valuation inputs that gives the highest priority to quoted prices in active markets for identical assets or liabilities and the lowest priority to unobservable inputs. The fair value hierarchy is as follows: •Level 1 Inputs—Unadjusted quoted prices in active markets for identical assets or liabilities that the Company has the ability to access at the measurement date. •Level 2 Inputs—Inputs other than quoted prices included in Level 1 that are observable for the asset or liability, either directly or indirectly. These might include quoted prices for similar assets or liabilities in active markets, quoted prices for identical or similar assets or liabilities in markets that are not active, inputs other than quoted prices that are observable for the asset or liability (such as interest rates, volatility, prepayment speeds, credit risks, etc.) or inputs that are derived principally from or corroborated by market data by correlation or other means. •Level 3 Inputs—Unobservable inputs for estimating the fair values of assets or liabilities that reflect the Company’s own assumptions about the assumptions that market participants would use in pricing the assets or liabilities. A description of the valuation methodologies used for instruments measured at fair value, as well as the general classification of such instruments pursuant to the valuation hierarchy, is set forth below. These valuation methodologies were applied to Busey’s assets and liabilities that are carried at fair value. In general, fair value estimates are based upon quoted market prices, when available. If such quoted market prices are not available, fair values are estimated utilizing independent valuation techniques that consider identical or similar securities for which significant assumptions are derived primarily from or corroborated by observable data. Valuation adjustments may be made to ensure that financial instruments are recorded at their estimated fair values. These adjustments may include amounts to reflect, among other things, counterparty credit quality and the company's creditworthiness as well as unobservable parameters. Any such valuation adjustments are applied consistently over time. While management believes Busey's valuation methodologies are appropriate and consistent with other market participants, the use of different methodologies or assumptions to estimate the fair value of certain financial instruments could result in a different estimate of fair value at the reporting date. Financial Assets and Financial Liabilities Measured at Fair Value on a Recurring Basis Debt Securities Available for Sale Debt securities classified as available for sale are reported at fair value, which is estimated using Level 2 inputs. Busey obtains fair value measurements from an independent pricing service. The independent pricing service utilizes evaluated pricing models that vary by asset class and incorporate available trade, bid, and other market information. Because many fixed income securities do not trade on a daily basis, the independent pricing service applies available information to prepare evaluations, with a focus on observable market data such as benchmark curves, benchmarking of like securities, sector groupings, and matrix pricing. The independent pricing service uses model processes, such as the Option Adjusted Spread model, to assess interest rate impact and develop prepayment scenarios. Models and processes take into account market conventions. For each asset class, a team of evaluators gathers information from market sources and integrates relevant credit information, perceived market movements, and sector news into the evaluated pricing applications and models. Market inputs that the independent pricing service normally seeks for evaluations of securities, listed in approximate order of priority, include: benchmark yields, reported trades, broker/dealer quotes, issuer spreads, two-sided markets, benchmark securities, bids, offers, and reference data including market research publications. The independent pricing service also monitors market indicators, industry, and economic events. For certain security types, additional inputs may be used or some of the market inputs may not be applicable. Evaluators may prioritize inputs differently on any given day for any security based on market conditions, and not all inputs listed are available for use in the evaluation process for each security evaluation on a given day. Because the data utilized was observable, the securities have been classified as Level 2. Equity Securities Equity securities are reported at fair value, which is estimated using Level 1 or Level 2 inputs. Fair value measurements of mutual funds or stock in active markets are estimated using unadjusted quoted prices for identical assets at the measurement date and are classified as Level 1. Fair value measurements of stock that are not active use quoted prices for identical or similar assets in markets and are classified as Level 2. Derivative Assets and Derivative Liabilities Busey’s derivative assets and derivative liabilities are reported at fair value, which is measured using Level 2 or Level 3 inputs. Fair values of derivative assets and liabilities are estimated based on prices that are obtained from a third-party which uses observable market inputs and, with the exception of risk participation agreements, are classified as Level 2. Due to the significance of unobservable inputs, derivative assets and liabilities related to risk participation agreements are classified as Level 3. Assets and Liabilities Measured at Fair Value on a Nonrecurring Basis Certain financial assets and financial liabilities are measured at estimated fair value on a non-recurring basis; that is, the instruments are not measured at estimated fair value on an ongoing basis but are subject to fair value adjustments in certain circumstances (for example, when there is evidence of impairment). Loans Evaluated Individually Busey does not record portfolio loans at estimated fair value on a recurring basis. However, periodically, a loan is evaluated individually and is reported at the estimated fair value of the underlying collateral, less estimated costs to sell, if repayment is expected solely from the collateral. If the estimated collateral value is not sufficient, a specific reserve is recorded. Collateral values are estimated using a combination of observable inputs, including recent appraisals, and unobservable inputs based on customized discounting criteria. Due to the significance of unobservable inputs, fair values of individually evaluated collateral dependent loans have been classified as Level 3. OREO and Other Repossessed Assets Non-financial assets measured at fair value, upon initial recognition or subsequent impairment, include OREO and other repossessed assets. OREO properties and other repossessed assets are measured using a combination of observable inputs, including recent appraisals, and unobservable inputs. Due to the significance of unobservable inputs, the estimated fair values of all OREO and other repossessed assets have been classified as Level 3.

PORTFOLIO LOANS - Schedule of Modified Loans with Subsequent Defaults (Details) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
	Sep. 30, 2025	Sep. 30, 2025
Term Extension
Distributions of portfolio loans
Loans with Subsequent Defaults	$ 3,571	$ 3,571
Payment Deferral
Distributions of portfolio loans
Loans with Subsequent Defaults		467
Commercial loans \| C&I and other commercial \| Term Extension
Distributions of portfolio loans
Loans with Subsequent Defaults	$ 3,571	3,571
Commercial loans \| C&I and other commercial \| Payment Deferral
Distributions of portfolio loans
Loans with Subsequent Defaults		$ 467

MERGERS AND ACQUISITIONS - Schedule of Reconciliation Between the Purchase Price and the Fair Value (Details) - USD ($) $ in Thousands	Mar. 01, 2025	Apr. 01, 2024
CrossFirst
PCD Financial Assets
Gross contractual receivable for PCD financial assets	$ 4,790,000
Fair value of PCD financial assets	4,700,000
CrossFirst \| Financial Asset Acquired with Credit Deterioration
PCD Financial Assets
Gross contractual receivable for PCD financial assets	1,539,718
ACL recorded for estimated uncollectible contractual cash flows specific to PCD financial assets	(100,783)
Interest premium (discount) specific to PCD financial assets	(3,063)
Loans previously charged-off by CrossFirst	(110,740)
Fair value of PCD financial assets	$ 1,325,132
M&M \| Financial Asset Acquired with Credit Deterioration
PCD Financial Assets
Gross contractual receivable for PCD financial assets		$ 29,290
ACL recorded for estimated uncollectible contractual cash flows specific to PCD financial assets		(1,243)
Interest premium (discount) specific to PCD financial assets		(1,773)
Loans previously charged-off by CrossFirst		0
Fair value of PCD financial assets		$ 26,274

STOCK-BASED COMPENSATION - 2020 Equity Plan (Details)	Sep. 30, 2025 shares
2020 Equity Plan
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Remaining shares available for issuance (in shares)	685,515

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

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-URI https://asc.fasb.org/1943274/2147480429/718-10-50-2

+ Details

PORTFOLIO LOANS (Tables)

9 Months Ended

Sep. 30, 2025

Accounts, Notes, Loans and Financing Receivable, Gross, Allowance, and Net [Abstract]

Schedule of Distribution of Portfolio Loans

Distributions of the loan portfolio by loan category and lending activity is presented in the following table:


	As of
(dollars in thousands)	September 30, 2025		December 31, 2024
Commercial loans
C&I and other commercial	$	4,395,871	$	1,904,515
CRE	5,424,095		3,269,564
Real estate construction	1,099,524		378,209
Total commercial loans	10,919,490		5,552,288
Retail loans
Retail real estate	2,196,246		1,696,457
Retail other	482,530		448,342
Total retail loans	2,678,776		2,144,799

Total portfolio loans	13,598,266		7,697,087
ACL	(174,181)		(83,404)
Portfolio loans, net	$	13,424,085	$	7,613,683

Schedule of Financial Instruments Owned and Pledged as Collateral


	As of
(dollars in thousands)	September 30, 2025		December 31, 2024
Pledged loans
FHLB	$	5,018,506	$	4,813,600
Federal Reserve Bank	1,973,933		765,824
Total pledged loans	$	6,992,439	$	5,579,424

To secure its obligations under derivative contracts, Busey pledged cash and held collateral as follows:


	As of
(dollars in thousands)	September 30, 2025		December 31, 2024
Cash pledged to secure obligations under derivative contracts	$	14,400	$	21,900
Collateral held to secure obligations under derivative contracts	8,140		20,260

Schedule of Risk Grades Segregated by Category and Class of Portfolio Loans

The following table is a summary of Busey’s portfolio loans by risk grade, segregated by loan category:


	As of September 30, 2025
(dollars in thousands)	Pass		Watch		Special Mention		Substandard		Substandard Non-accrual		Total
Commercial loans
C&I and other commercial	$	3,707,153	$	433,278	$	152,267	$	74,109	$	29,064	$	4,395,871
CRE	4,453,517		794,313		147,237		21,228		7,800		5,424,095
Real estate construction	1,011,685		56,664		25,653		5,227		295		1,099,524
Total commercial loans	9,172,355		1,284,255		325,157		100,564		37,159		10,919,490
Retail loans
Retail real estate	2,170,254		7,320		7,608		2,759		8,305		2,196,246
Retail other	481,892		—		—		6		632		482,530
Total retail loans	2,652,146		7,320		7,608		2,765		8,937		2,678,776
Total portfolio loans	$	11,824,501	$	1,291,575	$	332,765	$	103,329	$	46,096	$	13,598,266


	As of December 31, 2024
(dollars in thousands)	Pass		Watch		Special Mention		Substandard		Substandard Non-accrual		Total
Commercial loans
C&I and other commercial	$	1,545,338	$	281,424	$	36,152	$	37,749	$	3,852	$	1,904,515
CRE	2,744,018		438,945		55,041		16,507		15,053		3,269,564
Real estate construction	345,908		26,833		221		5,224		23		378,209
Total commercial loans	4,635,264		747,202		91,414		59,480		18,928		5,552,288
Retail loans
Retail real estate	1,680,640		9,408		882		2,543		2,984		1,696,457
Retail other	448,166		—		—		—		176		448,342
Total retail loans	2,128,806		9,408		882		2,543		3,160		2,144,799
Total portfolio loans	$	6,764,070	$	756,610	$	92,296	$	62,023	$	22,088	$	7,697,087

Schedule of Risk Grades of Portfolio Loans, Further Sorted by Origination

Risk grades of portfolio loans and gross charge-offs are presented in the tables below by lending activity, further sorted by origination year:


	As of and For The Nine Months Ended September 30, 2025
Risk Grade Ratings	Term Loans Amortized Cost Basis by Origination Year												Revolving Loans		Total
(dollars in thousands)	2025		2024		2023		2022		2021		Prior
C&I and other commercial
Pass	$	659,612	$	722,192	$	425,370	$	238,755	$	192,946	$	151,925	$	1,316,353	$	3,707,153
Watch	26,374		79,588		66,467		46,942		55,238		18,233		140,436		433,278
Special Mention	17,388		17,339		25,541		43,362		4,974		2,913		40,750		152,267
Substandard	10,422		1,965		16,543		4,216		10,159		3,771		27,033		74,109
Substandard non-accrual	4,601		2,343		644		1,318		640		5,048		14,470		29,064
Total C&I and other commercial	718,397		823,427		534,565		334,593		263,957		181,890		1,539,042		4,395,871
Gross charge-offs	$	1,246	$	2,626	$	4,347	$	1,440	$	13,591	$	11,254	$	4,550	$	39,054

CRE
Pass	631,171		487,489		703,228		1,216,265		776,293		600,081		38,990		4,453,517
Watch	169,711		56,362		139,202		156,277		186,841		83,665		2,255		794,313
Special Mention	50,239		23,098		5,093		14,139		37,467		16,067		1,134		147,237
Substandard	1,714		708		914		9,046		—		8,628		218		21,228
Substandard non-accrual	82		—		4,548		—		1		3,169		—		7,800
Total CRE	852,917		567,657		852,985		1,395,727		1,000,602		711,610		42,597		5,424,095
Gross charge-offs	1,297		11,057		—		—		253		—		—		12,607

Real estate construction
Pass	240,725		328,610		125,079		215,814		25,158		3,632		72,667		1,011,685
Watch	1,221		43,492		3,588		—		177		—		8,186		56,664
Special Mention	18,233		—		—		—		7,420		—		—		25,653
Substandard	5,165		—		—		—		62		—		—		5,227
Substandard non-accrual	—		274		—		—		21		—		—		295
Total real estate construction	265,344		372,376		128,667		215,814		32,838		3,632		80,853		1,099,524
Gross charge-offs	—		—		—		—		—		—		—		—

Retail real estate
Pass	111,695		138,069		304,874		457,128		379,646		533,444		245,398		2,170,254
Watch	2,696		606		489		1,520		280		1,160		569		7,320
Special Mention	69		84		4,052		1,479		1,705		—		219		7,608
Substandard	1,000		—		111		447		489		712		—		2,759
Substandard non-accrual	212		307		39		319		85		3,205		4,138		8,305
Total retail real estate	115,672		139,066		309,565		460,893		382,205		538,521		250,324		2,196,246
Gross charge-offs	85		—		—		—		—		51		36		172

Retail other
Pass	6,415		6,769		37,741		36,632		6,150		703		387,482		481,892
Watch	—		—		—		—		—		—		—		—
Special Mention	—		—		—		—		—		—		—		—
Substandard	—		—		—		—		—		6		—		6
Substandard non-accrual	35		—		93		99		—		—		405		632
Total retail other	6,450		6,769		37,834		36,731		6,150		709		387,887		482,530
Gross charge-offs	318		147		253		41		—		74		—		833

Total portfolio loans	$	1,958,780	$	1,909,295	$	1,863,616	$	2,443,758	$	1,685,752	$	1,436,362	$	2,300,703	$	13,598,266
Total gross charge-offs	$	2,946	$	13,830	$	4,600	$	1,481	$	13,844	$	11,379	$	4,586	$	52,666


	As of and For The Year Ended December 31, 2024
Risk Grade Ratings	Term Loans Amortized Cost Basis by Origination Year												Revolving Loans		Total
(dollars in thousands)	2024		2023		2022		2021		2020		Prior
C&I and other commercial
Pass	$	320,831	$	147,909	$	163,870	$	125,053	$	74,146	$	117,234	$	596,295	$	1,545,338
Watch	38,734		49,394		44,709		16,393		2,175		20,964		109,055		281,424
Special Mention	1,718		2,293		5,658		2,634		106		2,540		21,203		36,152
Substandard	15,186		6,545		788		591		320		2,424		11,895		37,749
Substandard non-accrual	65		141		464		—		42		852		2,288		3,852
Total C&I and other commercial	376,534		206,282		215,489		144,671		76,789		144,014		740,736		1,904,515
Gross charge-offs	$	—	$	14,980	$	148	$	22	$	—	$	303	$	—	$	15,453

CRE
Pass	291,503		354,591		755,266		645,994		356,867		314,340		25,457		2,744,018
Watch	115,078		132,900		60,611		62,408		28,320		38,733		895		438,945
Special Mention	39,252		643		8,020		1,395		4,165		1,517		49		55,041
Substandard	6,983		355		4,628		50		95		4,346		50		16,507
Substandard non-accrual	15,000		39		—		—		14		—		—		15,053
Total CRE	467,816		488,528		828,525		709,847		389,461		358,936		26,451		3,269,564
Gross charge-offs	—		—		—		2,999		—		315		—		3,314

Real estate construction
Pass	159,825		134,450		12,205		24,781		2,213		1,124		11,310		345,908
Watch	20,170		6,455		—		208		—		—		—		26,833
Special Mention	—		—		—		221		—		—		—		221
Substandard	5,224		—		—		—		—		—		—		5,224
Substandard non-accrual	—		—		—		23		—		—		—		23
Total real estate construction	185,219		140,905		12,205		25,233		2,213		1,124		11,310		378,209
Gross charge-offs	—		—		—		—		—		—		—		—

Retail real estate
Pass	101,582		237,306		366,820		354,380		147,236		267,431		205,885		1,680,640
Watch	1,255		550		2,733		3,377		872		124		497		9,408
Special Mention	151		—		344		—		—		372		15		882
Substandard	—		243		1,018		503		—		776		3		2,543
Substandard non-accrual	—		—		344		91		152		1,526		871		2,984
Total retail real estate	102,988		238,099		371,259		358,351		148,260		270,229		207,271		1,696,457
Gross charge-offs	—		—		—		—		—		168		—		168

Retail other
Pass	4,996		55,665		57,944		12,207		2,304		589		314,461		448,166



Substandard non-accrual	—		94		67		4		—		11		—		176
Total retail other	4,996		55,759		58,011		12,211		2,304		600		314,461		448,342
Gross charge-offs	9		31		106		78		4		403		—		631

Total portfolio loans	$	1,137,553	$	1,129,573	$	1,485,489	$	1,250,313	$	619,027	$	774,903	$	1,300,229	$	7,697,087
Total gross charge-offs	$	9	$	15,011	$	254	$	3,099	$	4	$	1,189	$	—	$	19,566

Schedule of Past Due and Non-accrual Loans

An analysis of portfolio loans that were past due and still accruing, or on a non-accrual status, is presented in the table below:


	As of September 30, 2025
	Loans past due, still accruing						Non-accrual Loans		Non-accrual Loans with No Allowance for Credit Losses
(dollars in thousands)	30-59 Days		60-89 Days		90+Days
Commercial loans
C&I and other commercial	$	996	$	1,450	$	861	$	29,064	$	6,685
CRE	2,815		6,289		78		7,800		1,543
Real estate construction	—		3,233		347		295		157
Past due and non-accrual commercial loans	3,811		10,972		1,286		37,159		8,385
Retail loans
Retail real estate	2,626		448		102		8,305		348
Retail other	929		128		30		632		—
Past due and non-accrual retail loans	3,555		576		132		8,937		348
Total past due and non-accrual loans	$	7,366	$	11,548	$	1,418	$	46,096	$	8,733


	As of December 31, 2024
	Loans past due, still accruing						Non-accrual Loans		Non-accrual Loans with No Allowance for Credit Losses
(dollars in thousands)	30-59 Days		60-89 Days		90+Days
Commercial loans
C&I and other commercial	$	95	$	—	$	—	$	3,852	$	1,224
CRE	42		2,759		—		15,053		15,000
Real estate construction	41		—		—		23		—
Past due and non-accrual commercial loans	178		2,759		—		18,928		16,224
Retail loans
Retail real estate	3,280		683		1,115		2,984		194
Retail other	1,094		130		34		176		—
Past due and non-accrual retail loans	4,374		813		1,149		3,160		194
Total past due and non-accrual loans	$	4,552	$	3,572	$	1,149	$	22,088	$	16,418

Schedule of Loan Modifications for Borrowers Experiencing Financial Difficulty

The following tables present the amortized cost basis of loans that were modified—specifically in the form of (1) principal forgiveness, (2) an interest rate reduction, (3) an other-than-insignificant payment deferral, and/or (4) a term extension—for borrowers experiencing financial difficulty during the periods indicated, disaggregated by lending activity and the type of modification:


	Three Months Ended September 30, 2025
(dollars in thousands)	Interest Rate Reduction		% of Total Class of Financing Receivable1		Payment Deferral		% of Total Class of Financing Receivable2		Term Extension		% of Total Class of Financing Receivable3
Modified Loans
C&I and other commercial	$	263	—	%	$	2,444	0.1	%	$	10,417	0.2	%
CRE	—		—	%	1,944		—	%	461		—	%



Total of loans modified during the period4	$	263	—	%	$	4,388	—	%	$	10,878	0.1	%

___________________________________________

1.Modified loans represented an insignificant portion of C&I and other commercial loans, and an insignificant portion of total loans, in both cases rounding to zero percent.

2.Modified loans represented an insignificant portion of CRE loans, and an insignificant portion of total loans, in both cases rounding to zero percent.

3.Modified loans represented an insignificant portion of CRE loans, rounding to zero percent.

4.All modifications were for loans classified as substandard.


	Three Months Ended September 30, 2024
(dollars in thousands)	Payment Deferral		% of Total Class of Financing Receivable1		Term Extension2		% of Total Class of Financing Receivable
Modified Loans
C&I and other commercial	$	325	—	%	$	14,537	0.8	%
CRE	—		—	%	18,448		0.5	%
Real estate construction	—		—	%	5,250		1.3	%


Total of loans modified during the period3	$	325	—	%	$	38,235	0.5	%

___________________________________________

1.Modified loans represented an insignificant portion of C&I and other commercial loans, and an insignificant portion of total loans, in both cases rounding to zero percent.

2.Modifications to extend loan terms also included, in some cases, interest rate increases during the extension period.

3.All modifications were for loans classified as substandard.


	Nine Months Ended September 30, 2025
(dollars in thousands)	Interest Rate Reduction		% of Total Class of Financing Receivable1		Payment Deferral		% of Total Class of Financing Receivable2		Term Extension		% of Total Class of Financing Receivable2
Modified Loans
C&I and other commercial	$	263	—	%	$	13,005	0.3	%	$	22,314	0.5	%
CRE	—		—	%	1,944		—	%	823		—	%
Real estate construction	—		—	%	—		—	%	5,165		0.5	%


Total of loans modified during the period3	$	263	—	%	$	14,949	0.1	%	$	28,302	0.2	%

___________________________________________

1.Modified loans represented an insignificant portion of C&I and other commercial loans, and an insignificant portion of total loans, in both cases rounding to zero percent.

2.Modified loans represented an insignificant portion of CRE loans, rounding to zero percent.

3.With the exception of two loans that were transferred to non-accrual status during the nine months ended September 30, 2025, all modifications were for loans classified as substandard.


	Nine Months Ended September 30, 2024
(dollars in thousands)	Payment Deferral1		% of Total Class of Financing Receivable2		Term Extension1		% of Total Class of Financing Receivable
Modified Loans
C&I and other commercial	$	325	—	%	$	28,073	1.5	%
CRE	—		—	%	19,782		0.6	%
Real estate construction	—		—	%	5,250		1.3	%


Total of loans modified during the period3	$	325	—	%	$	53,105	0.7	%

___________________________________________

1.Modifications to extend loan terms also included, in some cases, interest rate increases during the extension period.

2.Modified loans represented an insignificant portion of C&I and other commercial loans, rounding to zero percent.

3.All modifications were for loans classified as substandard.

The following table provides, by lending activity, the weighted average interest rate reductions and term extensions for loan modifications made during the periods indicated for borrowers experiencing financial difficulty:


	Three Months Ended September 30,			Nine Months Ended September 30,
	2025				2024	2025				2024
	Weighted Average Interest Rate Reduction		Weighted Average Term Extension			Weighted Average Term Extension	Weighted Average Interest Rate Reduction		Weighted Average Term Extension		Weighted Average Term Extension
C&I and other commercial	5.00	%	6 months			6 months	5.00	%	10 months		1.2 years
CRE	—	%	8 months			4 months	—	%	1.3 years		4 months
Real estate construction	—	%	—			6 months	—	%	1.3 years		6 months


Aggregate effect	5.00	%	6 months			5 months	5.00	%	11 months		10 months

The following table depicts the payment performance of loans modified during the last twelve months:


	As of September 30, 2025
(dollars in thousands)	Current		30-89 Days		90+ Days		Non-accrual
Modified Loans
C&I and other commercial	$	32,062	$	—	$	—	$	4,038
CRE	4,147		—		—		—
Real estate construction	5,165		—		—		—


Loans modified during the last twelve months	$	41,374	$	—	$	—	$	4,038

Schedule of Modified Loans with Subsequent Defaults

A default occurs when a loan is 90 days or more past due or transferred to non-accrual status. The following table presents loans that defaulted after having been modified during the twelve months before the default.


	Three Months Ended September 30,		Nine Months Ended September 30,
	2025			2025
(dollars in thousands)	Term Extension				Payment Deferral		Term Extension
Loans with Subsequent Defaults
C&I and other commercial	$	3,571			$	467	$	3,571




Modified loans with subsequent defaults	$	3,571			$	467	$	3,571

Schedule of ACL and Amortized Cost of Portfolio Loans by Loan Category

The following tables summarize activity in the ACL attributable to each lending activity. Allocation of a portion of the ACL to one lending activity does not preclude its availability to absorb losses from other lending activities:


	Three Months Ended September 30, 2025
(dollars in thousands)	C&I and Other Commercial		CRE		Real Estate Construction		Retail Real Estate		Retail Other		Total
ACL balance, June 30, 2025	$	68,578	$	70,935	$	13,072	$	29,042	$	1,707	$	183,334


Provision for loan losses	(4,768)		1,323		(880)		739		281		(3,305)
Charged-off	(5,753)		(1,438)		—		(53)		(204)		(7,448)
Recoveries	1,379		24		1		115		81		1,600
ACL balance, September 30, 2025	$	59,436	$	70,844	$	12,193	$	29,843	$	1,865	$	174,181


	Three Months Ended September 30, 2024
(dollars in thousands)	C&I and Other Commercial		CRE		Real Estate Construction		Retail Real Estate		Retail Other		Total
ACL balance, June 30, 2024	$	20,286	$	35,104	$	3,722	$	23,729	$	2,385	$	85,226

Provision for loan losses	715		(1,158)		39		120		286		2
Charged-off	(202)		(215)		—		(32)		(225)		(674)
Recoveries	210		4		10		162		41		427
ACL balance, September 30, 2024	$	21,009	$	33,735	$	3,771	$	23,979	$	2,487	$	84,981


	Nine Months Ended September 30, 2025
(dollars in thousands)	C&I and Other Commercial		CRE		Real Estate Construction		Retail Real Estate		Retail Other		Total
ACL balance, December 31, 2024	$	21,589	$	32,301	$	3,345	$	23,711	$	2,458	$	83,404
Day 1 PCD1	75,569		21,588		2,112		1,430		84		100,783
Day 2 Provision for loan losses2	22,648		15,104		2,911		1,628		142		42,433
Provision for loan losses	(23,008)		14,300		3,731		2,833		(137)		(2,281)
Charged-off	(39,054)		(12,607)		—		(172)		(833)		(52,666)
Recoveries	1,692		158		94		413		151		2,508
ACL balance, September 30, 2025	$	59,436	$	70,844	$	12,193	$	29,843	$	1,865	$	174,181

___________________________________________

1.The Day 1 PCD is attributable to the CrossFirst acquisition (see “Note 2. Mergers and Acquisitions”), and represents the initial adjustment to the fair value of the PCD loans.

2.The Day 2 provision for loan losses is attributable to the CrossFirst acquisition (see “Note 2. Mergers and Acquisitions”), and represents the initial provision for non-PCD loans.


	Nine Months Ended September 30, 2024
(dollars in thousands)	C&I and Other Commercial		CRE		Real Estate Construction		Retail Real Estate		Retail Other		Total
ACL balance, December 31, 2023	$	21,256	$	35,465	$	5,163	$	26,298	$	3,558	$	91,740
Day 1 PCD1	824		322		—		96		1		1,243
Provision for loan losses	13,958		(1,882)		(1,449)		(2,624)		(686)		7,317
Charged-off	(15,433)		(315)		—		(159)		(503)		(16,410)
Recoveries	404		145		57		368		117		1,091
ACL balance, September 30, 2024	$	21,009	$	33,735	$	3,771	$	23,979	$	2,487	$	84,981

___________________________________________

1.The Day 1 PCD is attributable to the M&M acquisition (see “Note 2. Mergers and Acquisitions.”)

DERIVATIVE FINANCIAL INSTRUMENTS - Schedule of Mortgage Banking Derivatives (Details) - USD ($) $ in Thousands	Sep. 30, 2025	Dec. 31, 2024
Interest rate lock commitments
Mortgage banking derivative assets
Derivative asset, statement of financial position [Extensible Enumeration]	Other assets	Other assets
Notional Amount	$ 6,515	$ 2,430
Fair value recorded in other assets	$ 132	$ 28
Mortgage banking derivative liabilities
Derivative liability, statement of financial position [Extensible Enumeration]	Other liabilities	Other liabilities
Notional Amount	$ 0	$ 436
Fair value recorded in other liabilities	0	4
Forward sales commitments
Mortgage banking derivative assets
Notional Amount	4,679	3,457
Fair value recorded in other assets	19	21
Mortgage banking derivative liabilities
Notional Amount	9,290	1,955
Fair value recorded in other liabilities	78	6
Mortgage banking derivative assets \| Designated as Hedging Instrument
Mortgage banking derivative assets
Notional Amount	11,194	5,887
Fair value recorded in other assets	151	49
Mortgage banking derivative liabilities
Notional Amount	9,290	2,391
Fair value recorded in other liabilities	$ 78	$ 10

EARNINGS PER COMMON SHARE

9 Months Ended

Sep. 30, 2025

Earnings Per Share [Abstract]

EARNINGS PER COMMON SHARE

NOTE 14. EARNINGS PER COMMON SHARE

Basic earnings per common share is computed by dividing net income available to common stockholders by the weighted average number of common shares outstanding, which include DSUs that are vested but not delivered. Net income available to common stockholders is net income less dividends that have been declared on Busey’s preferred stock (all of which is non-cumulative). Diluted earnings per common share is computed using the treasury stock method and reflects the potential dilution that could occur if Busey’s outstanding stock options and SSARs were exercised, stock units were vested, and ESPP shares were issued.

Earnings per common share have been computed as follows:


	Three Months Ended September 30,				Nine Months Ended September 30,
(dollars in thousands, except per share amounts)	2025		2024		2025		2024
Net income	$	57,098	$	32,004	$	74,512	$	85,586
Dividends on preferred stock	(5,131)		—		(5,286)		—
Net income available to common stockholders	$	51,967	$	32,004	$	69,226	$	85,586

Weighted average number of common shares outstanding, basic	89,136,898		57,033,359		82,508,723		56,458,430
Dilutive effect of common stock equivalents:
Options	187		1,714		63		572

SSARs	204,106		—		191,460		—
RSU awards	815,829		655,224		817,169		662,609
PSU awards	32,510		254,365		65,031		264,451
DSU awards	17,204		16,766		15,656		18,390
ESPP	11,648		6,420		11,897		6,847
Weighted average number of common shares outstanding, diluted	90,218,382		57,967,848		83,609,999		57,411,299

Basic earnings per common share	$	0.58	$	0.56	$	0.84	$	1.52
Diluted earnings per common share	$	0.58	$	0.55	$	0.83	$	1.49

Shares that were excluded from the computation of diluted earnings per common share because their effect would have been anti-dilutive are summarized in the table below for the periods presented:


	Three Months Ended September 30,		Nine Months Ended September 30,
	2025	2024	2025	2024
Anti-dilutive common stock equivalents
Options	—	—	10,071	12,784


RSU awards	—	—	1,498	4,288
PSU awards	298,211	107,065	238,099	103,001


Total anti-dilutive common stock equivalents	298,211	107,065	249,668	120,073

DEBT SECURITIES - Schedule of Realized Gains and Losses on Debt Securities (Details) - USD ($) $ in Thousands	3 Months Ended				9 Months Ended
	Sep. 30, 2025	Mar. 31, 2025	Sep. 30, 2024	Mar. 31, 2024	Sep. 30, 2025	Sep. 30, 2024
Realized gains and losses on debt securities
Gross gains on debt securities	$ 0		$ 0		$ 9	$ 1
Gross (losses) on debt securities	(13)		(11)		(15,558)	(6,818)
Realized net gains (losses) on debt securities	$ (13)		$ (11)		$ (15,549)	$ (6,817)
Debt securities available for sale, sold		$ 205,600		$ 108,200
Pre-tax loss on debt securities		15,500		6,800
Debt securities available for sale sold, tax benefit		$ 4,100		$ 1,800

DEBT SECURITIES

9 Months Ended

Sep. 30, 2025

Investments, Debt and Equity Securities [Abstract]

DEBT SECURITIES

NOTE 3. DEBT SECURITIES

Busey's portfolio of debt securities includes both available for sale and held to maturity securities. The tables below provide the amortized cost, unrealized or unrecognized gains and losses, and fair values of debt securities summarized by major category:


	As of September 30, 2025
(dollars in thousands)	Amortized Cost		Unrealized				Fair Value
			Gross Gains		Gross Losses
Debt securities available for sale1

Obligations of U.S. government corporations and agencies	$	113,676	$	124	$	(195)	$	113,605
Obligations of states and political subdivisions	259,470		655		(12,581)		247,544
Asset-backed securities	285,052		510		—		285,562
Commercial mortgage-backed securities	147,183		541		(11,743)		135,981
Residential mortgage-backed securities	1,395,849		7,513		(135,786)		1,267,576
Corporate debt securities	50,501		410		(1,920)		48,991
Total debt securities available for sale	$	2,251,731	$	9,753	$	(162,225)	$	2,099,259



	Amortized Cost		Unrecognized				Fair Value
			Gross Gains		Gross Losses
Debt securities held to maturity
Commercial mortgage-backed securities	$	398,375	$	—	$	(68,743)	$	329,632
Residential mortgage-backed securities	386,446		—		(56,607)		329,839
Total debt securities held to maturity	$	784,821	$	—	$	(125,350)	$	659,471

___________________________________________

1.This table includes debt securities marked at par, with no gain or loss.


	As of December 31, 2024
(dollars in thousands)	Amortized Cost		Unrealized				Fair Value
			Gross Gains		Gross Losses
Debt securities available for sale1

Obligations of U.S. government corporations and agencies	$	1,408	$	—	$	(8)	$	1,400
Obligations of states and political subdivisions	156,534		31		(16,736)		139,829
Asset-backed securities	336,379		181		(3)		336,557
Commercial mortgage-backed securities	107,305		—		(15,131)		92,174
Residential mortgage-backed securities	1,279,090		19		(191,899)		1,087,210
Corporate debt securities	159,236		363		(6,548)		153,051
Total debt securities available for sale	$	2,039,952	$	594	$	(230,325)	$	1,810,221



	Amortized Cost		Unrecognized				Fair Value
			Gross Gains		Gross Losses
Debt securities held to maturity
Commercial mortgage-backed securities	$	415,530	$	—	$	(77,242)	$	338,288
Residential mortgage-backed securities	411,100		—		(74,335)		336,765
Total debt securities held to maturity	$	826,630	$	—	$	(151,577)	$	675,053

___________________________________________

1.This table includes debt securities marked at par, with no gain or loss.

Maturities of Debt Securities

Amortized cost and fair value of debt securities, by contractual maturity or pre-refunded date, are shown below. Mortgages underlying mortgage-backed securities and asset-backed securities may be called or prepaid; therefore, actual maturities could differ from the contractual maturities. All mortgage-backed securities were issued by U.S. government corporations and agencies.


	As of September 30, 2025
(dollars in thousands)	Amortized Cost		Fair Value
Debt securities available for sale
Due in one year or less	$	13,055	$	12,989
Due after one year through five years	59,849		57,288
Due after five years through ten years	373,230		359,557
Due after ten years	1,805,597		1,669,425
Debt securities available for sale	$	2,251,731	$	2,099,259

Debt securities held to maturity
Due in one year or less	$	31,564	$	31,320
Due after one year through five years	38,433		36,972
Due after five years through ten years	14,719		13,268
Due after ten years	700,105		577,911
Debt securities held to maturity	$	784,821	$	659,471

Gains and Losses on Debt Securities Available for Sale

Realized gains and losses related to sales and calls of debt securities available for sale are summarized as follows:


	Three Months Ended September 30,				Nine Months Ended September 30,
(dollars in thousands)	2025		2024		2025		2024
Realized gains and losses on debt securities
Gross gains on debt securities	$	—	$	—	$	9	$	1
Gross (losses) on debt securities1	(13)		(11)		(15,558)		(6,818)
Realized net gains (losses) on debt securities	$	(13)	$	(11)	$	(15,549)	$	(6,817)

___________________________________________

Debt securities with carrying amounts of $741.8 million on September 30, 2025, and $871.4 million on December 31, 2024, were pledged as collateral for public deposits, securities sold under agreements to repurchase, and for other purposes as required.

Debt Securities in an Unrealized or Unrecognized Loss Position


	As of September 30, 2025
	Less than 12 months				12 months or more				Total
(dollars in thousands)	Fair Value		Unrealized Losses		Fair Value		Unrealized Losses		Fair Value		Unrealized Losses
Debt securities available for sale

Obligations of U.S. government corporations and agencies	$	69,984	$	(195)	$	—	$	—	$	69,984	$	(195)
Obligations of states and political subdivisions	99,487		(2,375)		95,200		(10,206)		194,687		(12,581)

Commercial mortgage-backed securities	5,813		(61)		72,141		(11,682)		77,954		(11,743)
Residential mortgage-backed securities	1,427		(1)		782,258		(135,785)		783,685		(135,786)
Corporate debt securities	5,967		(18)		30,956		(1,902)		36,923		(1,920)
Debt securities available for sale with gross unrealized losses	$	182,678	$	(2,650)	$	980,555	$	(159,575)	$	1,163,233	$	(162,225)




	Fair Value		Unrecognized Losses		Fair Value		Unrecognized Losses
Debt securities held to maturity
Commercial mortgage-backed securities	$	329,632	$	(68,743)	$	329,632	$	(68,743)
Residential mortgage-backed securities	329,839		(56,607)		329,839		(56,607)
Debt securities held to maturity with gross unrecognized losses	$	659,471	$	(125,350)	$	659,471	$	(125,350)


	As of December 31, 2024
	Less than 12 months				12 months or more				Total
(dollars in thousands)	Fair Value		Unrealized Losses		Fair Value		Unrealized Losses		Fair Value		Unrealized Losses
Debt securities available for sale

Obligations of U.S. government corporations and agencies	$	—	$	—	$	1,328	$	(8)	$	1,328	$	(8)
Obligations of states and political subdivisions	11,234		(209)		119,723		(16,527)		130,957		(16,736)
Asset-backed securities	14,997		(3)		—		—		14,997		(3)
Commercial mortgage-backed securities	6,238		(42)		85,936		(15,089)		92,174		(15,131)
Residential mortgage-backed securities	152,081		(640)		930,642		(191,259)		1,082,723		(191,899)
Corporate debt securities	598		(1)		143,966		(6,547)		144,564		(6,548)
Debt securities available for sale with gross unrealized losses	$	185,148	$	(895)	$	1,281,595	$	(229,430)	$	1,466,743	$	(230,325)




	Fair Value		Unrecognized Losses		Fair Value		Unrecognized Losses
Debt securities held to maturity
Commercial mortgage-backed securities	$	338,288	$	(77,242)	$	338,288	$	(77,242)
Residential mortgage-backed securities	336,765		(74,335)		336,765		(74,335)
Debt securities held to maturity with gross unrecognized losses	$	675,053	$	(151,577)	$	675,053	$	(151,577)

Additional information about debt securities in an unrealized or unrecognized loss position is presented in the tables below:


	As of September 30, 2025
(dollars in thousands)	Available for Sale			Held to Maturity			Total
Debt securities with gross unrealized or unrecognized losses, fair value	$	1,163,233		$	659,471		$	1,822,704
Gross unrealized or unrecognized losses on debt securities	162,225			125,350			287,575
Ratio of gross unrealized or unrecognized losses to debt securities with gross unrealized or unrecognized losses	13.9		%	19.0		%	15.8		%

Count of debt securities	632			55			687
Count of debt securities in an unrealized or unrecognized loss position	428			55			483


	As of December 31, 2024
(dollars in thousands)	Available for Sale			Held to Maturity			Total
Debt securities with gross unrealized or unrecognized losses, fair value	$	1,466,743		$	675,053		$	2,141,796
Gross unrealized or unrecognized losses on debt securities	230,325			151,577			381,902
Ratio of gross unrealized or unrecognized losses to debt securities with gross unrealized or unrecognized losses	15.7		%	22.5		%	17.8		%

Count of debt securities	677			55			732
Count of debt securities in an unrealized or unrecognized loss position	586			55			641

Unrealized and unrecognized losses are related to changes in market interest rates and market conditions that do not represent credit-related impairments. Unless part of a corporate strategy or repositioning plan, Busey does not intend to sell securities that are in an unrealized or unrecognized loss position, and it is more likely than not that Busey will recover the amortized cost prior to being required to sell the debt securities. Full collection of the amounts due according to the contractual terms of the debt securities is expected; therefore, no ACL has been recorded in relation to debt securities, and the impairment related to noncredit factors on debt securities available for sale is recognized in AOCI, net of applicable taxes. As of September 30, 2025, Busey did not hold general obligation bonds of any single issuer that exceeded, in aggregate, 10% of Busey’s stockholders’ equity.

PORTFOLIO LOANS - Schedule of Distribution of Portfolio Loans (Details) - USD ($) $ in Thousands	Sep. 30, 2025	Jun. 30, 2025	Dec. 31, 2024	Sep. 30, 2024	Jun. 30, 2024	Dec. 31, 2023
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total portfolio loans	$ 13,598,266		$ 7,697,087
ACL	(174,181)	$ (183,334)	(83,404)	$ (84,981)	$ (85,226)	$ (91,740)
Portfolio loans, net	13,424,085		7,613,683
Commercial loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total portfolio loans	10,919,490		5,552,288
Commercial loans \| C&I and other commercial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total portfolio loans	4,395,871		1,904,515
ACL	(59,436)	(68,578)	(21,589)	(21,009)	(20,286)	(21,256)
Commercial loans \| CRE
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total portfolio loans	5,424,095		3,269,564
ACL	(70,844)	(70,935)	(32,301)	(33,735)	(35,104)	(35,465)
Commercial loans \| Real estate construction
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total portfolio loans	1,099,524		378,209
ACL	(12,193)	(13,072)	(3,345)	(3,771)	(3,722)	(5,163)
Retail loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total portfolio loans	2,678,776		2,144,799
Retail loans \| CRE
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total portfolio loans	2,196,246		1,696,457
ACL	(29,843)	(29,042)	(23,711)	(23,979)	(23,729)	(26,298)
Retail loans \| Retail other
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total portfolio loans	482,530		448,342
ACL	$ (1,865)	$ (1,707)	$ (2,458)	$ (2,487)	$ (2,385)	$ (3,558)

LEASES - Schedule of Future Minimum Lease Payments (Details) $ in Thousands	Sep. 30, 2025 USD ($)
Rents to be received
Remainder of 2025	$ 211
2026	738
2027	515
2028	377
2029	197
2030	117
Total lease payments from operating leases	$ 2,155

PORTFOLIO LOANS - Schedule of Past Due and Non-accrual Loans (Details) - USD ($) $ in Thousands	Sep. 30, 2025	Dec. 31, 2024
Financing Receivable, Past Due [Line Items]
Total portfolio loans	$ 13,598,266	$ 7,697,087
90+ days past due and still accruing	1,418	1,149
Non-accrual Loans	46,096	22,088
Non-accrual Loans with No Allowance for Credit Losses	8,733	16,418
30 to 59 days past due and still accruing
Financing Receivable, Past Due [Line Items]
Total portfolio loans	7,366	4,552
60 to 89 days past due and still accruing
Financing Receivable, Past Due [Line Items]
Total portfolio loans	11,548	3,572
Commercial loans
Financing Receivable, Past Due [Line Items]
Total portfolio loans	10,919,490	5,552,288
90+ days past due and still accruing	1,286	0
Non-accrual Loans	37,159	18,928
Non-accrual Loans with No Allowance for Credit Losses	8,385	16,224
Commercial loans \| 30 to 59 days past due and still accruing
Financing Receivable, Past Due [Line Items]
Total portfolio loans	3,811	178
Commercial loans \| 60 to 89 days past due and still accruing
Financing Receivable, Past Due [Line Items]
Total portfolio loans	10,972	2,759
Commercial loans \| C&I and other commercial
Financing Receivable, Past Due [Line Items]
Total portfolio loans	4,395,871	1,904,515
90+ days past due and still accruing	861	0
Non-accrual Loans	29,064	3,852
Non-accrual Loans with No Allowance for Credit Losses	6,685	1,224
Commercial loans \| C&I and other commercial \| 30 to 59 days past due and still accruing
Financing Receivable, Past Due [Line Items]
Total portfolio loans	996	95
Commercial loans \| C&I and other commercial \| 60 to 89 days past due and still accruing
Financing Receivable, Past Due [Line Items]
Total portfolio loans	1,450	0
Commercial loans \| CRE
Financing Receivable, Past Due [Line Items]
Total portfolio loans	5,424,095	3,269,564
90+ days past due and still accruing	78	0
Non-accrual Loans	7,800	15,053
Non-accrual Loans with No Allowance for Credit Losses	1,543	15,000
Commercial loans \| CRE \| 30 to 59 days past due and still accruing
Financing Receivable, Past Due [Line Items]
Total portfolio loans	2,815	42
Commercial loans \| CRE \| 60 to 89 days past due and still accruing
Financing Receivable, Past Due [Line Items]
Total portfolio loans	6,289	2,759
Commercial loans \| Real estate construction
Financing Receivable, Past Due [Line Items]
Total portfolio loans	1,099,524	378,209
90+ days past due and still accruing	347	0
Non-accrual Loans	295	23
Non-accrual Loans with No Allowance for Credit Losses	157	0
Commercial loans \| Real estate construction \| 30 to 59 days past due and still accruing
Financing Receivable, Past Due [Line Items]
Total portfolio loans	0	41
Commercial loans \| Real estate construction \| 60 to 89 days past due and still accruing
Financing Receivable, Past Due [Line Items]
Total portfolio loans	3,233	0
Retail loans
Financing Receivable, Past Due [Line Items]
Total portfolio loans	2,678,776	2,144,799
90+ days past due and still accruing	132	1,149
Non-accrual Loans	8,937	3,160
Non-accrual Loans with No Allowance for Credit Losses	348	194
Retail loans \| 30 to 59 days past due and still accruing
Financing Receivable, Past Due [Line Items]
Total portfolio loans	3,555	4,374
Retail loans \| 60 to 89 days past due and still accruing
Financing Receivable, Past Due [Line Items]
Total portfolio loans	576	813
Retail loans \| CRE
Financing Receivable, Past Due [Line Items]
Total portfolio loans	2,196,246	1,696,457
90+ days past due and still accruing	102	1,115
Non-accrual Loans	8,305	2,984
Non-accrual Loans with No Allowance for Credit Losses	348	194
Retail loans \| CRE \| 30 to 59 days past due and still accruing
Financing Receivable, Past Due [Line Items]
Total portfolio loans	2,626	3,280
Retail loans \| CRE \| 60 to 89 days past due and still accruing
Financing Receivable, Past Due [Line Items]
Total portfolio loans	448	683
Retail loans \| Retail other
Financing Receivable, Past Due [Line Items]
Total portfolio loans	482,530	448,342
90+ days past due and still accruing	30	34
Non-accrual Loans	632	176
Non-accrual Loans with No Allowance for Credit Losses	0	0
Retail loans \| Retail other \| 30 to 59 days past due and still accruing
Financing Receivable, Past Due [Line Items]
Total portfolio loans	929	1,094
Retail loans \| Retail other \| 60 to 89 days past due and still accruing
Financing Receivable, Past Due [Line Items]
Total portfolio loans	$ 128	$ 130

OPERATING SEGMENTS AND RELATED INFORMATION

9 Months Ended

Sep. 30, 2025

Segment Reporting [Abstract]

OPERATING SEGMENTS AND RELATED INFORMATION

NOTE 16. OPERATING SEGMENTS AND RELATED INFORMATION

Busey’s reportable segments are determined by its chief executive officer, who is the designated chief operating decision maker. Busey is organized into three reportable operating segments: Banking, Wealth Management, and FirsTech. These operating segments are strategic business units that are separately managed, as they offer different products and services and have different marketing strategies.

Banking

The Banking operating segment provides a full range of banking services to individual and corporate customers through First Busey Corporation’s wholly-owned bank subsidiary, Busey Bank.

Busey Bank has 79 banking centers located throughout Illinois; the St. Louis, Missouri MSA; southwest Florida; Indianapolis, Indiana; the Dallas-Fort Worth MSA; the Kansas City MSA; Wichita Kansas; Oklahoma City and Tulsa Oklahoma; Phoenix and Tucson, Arizona; Denver and Colorado Springs, Colorado; and Clayton, New Mexico.

Banking services offered to individual customers include customary types of demand and savings deposits, money transfers, safe deposit services, individual retirement accounts and other fiduciary services, automated teller machines, and technology-based networks, as well as a variety of loan products including residential real estate, home equity lines of credit, and consumer loans. Banking services offered to corporate customers include commercial, CRE, real estate construction, and agricultural loans, as well as commercial depository services such as cash management.

Wealth Management

The Wealth Management operating segment provides a full range of asset management, investment, brokerage, fiduciary, philanthropic advisory, tax preparation, and farm management services to individuals, businesses, and foundations. Services are provided through Busey Capital Management, Inc., a wholly-owned subsidiary of Busey Bank, and Busey Wealth Management, a division of Busey Bank.

Wealth management services tailored to individuals include trust and estate advisory services and financial planning. Business services include business succession planning and employee retirement plan services. Services for foundations include investment strategy consulting and fiduciary services.

FirsTech

The FirsTech operating segment provides comprehensive and innovative payment technology solutions through Busey Bank’s wholly-owned subsidiary, FirsTech. FirsTech's multi-channel payment platform allows businesses to collect payments from their customers in a variety of ways to enable fast, frictionless payments. Payment method vehicles include, but are not limited to, text-based mobile bill pay; interactive voice response; electronic payment concentration delivered to Automated Clearing House networks, money management, and credit card networks; walk-in payment processing for customers at retail pay agents; customer service payments made over a telephone; direct debit services; merchant services referral solutions serving partner Financial Institutions and their business customers; and lockbox remittance processing for customers to make payments by mail. FirsTech also provides additional tools to help clients with billing, reconciliation, bill reminders, and treasury services.

FirsTech's client base represents a diverse set of industries, with a higher concentration in highly regulated industries, such as financial institutions, utility, insurance, and telecommunications industries.

Segment Financial Information

The segment financial information provided below has been derived from information used by management to monitor and manage Busey’s financial performance. The accounting policies of Busey’s operating segments are the same as those described in the summary of significant accounting policies in “Note 1. Significant Accounting Policies” of Busey’s 2024 Annual Report. Busey accounts for intersegment revenue and transfers at current market prices.


	As of September 30, 2025
(dollars in thousands)	Banking		Wealth Management		FirsTech		Other		Total
Goodwill	$	360,223	$	14,108	$	8,992	$	—	$	383,323
Total assets	17,972,441		144,882		45,909		25,396		18,188,628


	As of December 31, 2024
(dollars in thousands)	Banking		Wealth Management		FirsTech		Other		Total
Goodwill	$	310,595	$	14,108	$	8,992	$	—	$	333,695
Total assets	11,856,651		126,180		57,737		6,154		12,046,722

Financial results by operating segment, including significant expense categories provided to the chief operating decision maker, are summarized below:


	Three Months Ended September 30, 2025
(dollars in thousands)	Banking		Wealth Management		FirsTech		Other		Total
Interest income	$	244,504	$	—	$	—	$	1	$	244,505
Intersegment interest income	—		—		16		(16)		—
Interest expense	86,524		—		—		2,844		89,368
Intersegment interest expense	951		—		—		(951)		—
Net interest income	157,029		—		16		(1,908)		155,137
Provision for credit losses	(985)		—		—		—		(985)
Net interest income after provision for credit losses	158,014		—		16		(1,908)		156,122

Noninterest income
Wealth management fees	—		17,184		—		—		17,184
Payment technology solutions	—		—		5,092		—		5,092
Treasury management services	4,598		—		—		—		4,598
Card services and ATM fees	4,799		—		—		—		4,799
Other service charges on deposit accounts	1,617		—		—		—		1,617
All other noninterest income	5,957		183		(4)		1,772		7,908
Intersegment noninterest income	564		—		443		(1,007)		—
Noninterest income	17,535		17,367		5,531		765		41,198

Revenue	174,564		17,367		5,547		(1,143)		196,335

Noninterest expense
Salaries, wages, and employee benefits	53,264		7,576		2,620		10,685		74,145
Data processing	8,062		658		931		63		9,714
Amortization of intangible assets	4,292		215		—		—		4,507
Interchange expense	—		—		1,336		—		1,336
All other noninterest expense	26,706		562		674		2,374		30,316
Intersegment noninterest expense	4,346		885		404		(5,635)		—
Noninterest expense	96,670		9,896		5,965		7,487		120,018

Income (loss) before income taxes	78,879		7,471		(418)		(8,630)		77,302
Income taxes	21,283		1,793		(112)		(2,760)		20,204
Net income	$	57,596	$	5,678	$	(306)	$	(5,870)	$	57,098


	Three Months Ended September 30, 2024
(dollars in thousands)	Banking		Wealth Management		FirsTech		Other		Total
Interest income	$	134,598	$	—	$	—	$	8	$	134,606
Intersegment interest income	—		—		12		(12)		—
Interest expense	47,611		—		—		4,348		51,959
Intersegment interest expense	457		—		—		(457)		—
Net interest income	86,530		—		12		(3,895)		82,647
Provision for credit losses	409		—		—		—		409
Net interest income after provision for credit losses	86,121		—		12		(3,895)		82,238

Noninterest income
Wealth management fees	—		15,378		—		—		15,378
Payment technology solutions	—		—		5,265		—		5,265
Treasury management services	2,201		—		—		—		2,201
Card services and ATM fees	3,557		—		—		—		3,557
Other service charges on deposit accounts	2,390		—		—		—		2,390
All other noninterest income	5,431		791		(1)		833		7,054
Intersegment noninterest income	372		—		286		(658)		—
Noninterest income	13,951		16,169		5,550		175		35,845

Revenue	100,481		16,169		5,562		(3,720)		118,492

Noninterest expense
Salaries, wages, and employee benefits	29,615		6,606		2,357		6,015		44,593
Data processing	5,298		544		938		130		6,910
Amortization of intangible assets	2,268		280		—		—		2,548
Interchange expense	—		—		1,352		—		1,352
All other noninterest expense	16,273		573		639		2,631		20,116
Intersegment noninterest expense	2,879		774		361		(4,014)		—
Noninterest expense	56,333		8,777		5,647		4,762		75,519

Income (loss) before income taxes	43,739		7,392		(85)		(8,482)		42,564
Income taxes	10,518		1,774		(24)		(1,708)		10,560
Net income	$	33,221	$	5,618	$	(61)	$	(6,774)	$	32,004


	Nine Months Ended September 30, 2025
(dollars in thousands)	Banking		Wealth Management		FirsTech		Other		Total
Interest income	$	658,760	$	—	$	—	$	6	$	658,766
Intersegment interest income	—		—		46		(46)		—
Interest expense	235,288		—		—		11,427		246,715
Intersegment interest expense	2,308		—		—		(2,308)		—
Net interest income	421,164		—		46		(9,159)		412,051
Provision for credit losses	50,308		—		—		—		50,308
Net interest income after provision for credit losses	370,856		—		46		(9,159)		361,743

Noninterest income
Wealth management fees	—		51,325		—		—		51,325
Payment technology solutions	—		—		15,121		—		15,121
Treasury management services	12,596		—		—		—		12,596
Card services and ATM fees	13,388		—		—		—		13,388
Other service charges on deposit accounts	4,663		—		—		—		4,663
All other noninterest income	2,134		594		(6)		7,469		10,191
Intersegment noninterest income	1,232		—		1,217		(2,449)		—
Noninterest income	34,013		51,919		16,332		5,020		107,284

Revenue	455,177		51,919		16,378		(4,139)		519,335

Noninterest expense
Salaries, wages, and employee benefits	157,237		21,713		7,952		33,166		220,068
Data processing	28,392		1,873		2,790		255		33,310
Amortization of intangible assets	11,497		685		—		—		12,182
Interchange expense	—		—		3,976		—		3,976
All other noninterest expense	72,693		1,889		2,009		13,754		90,345
Intersegment noninterest expense	14,167		2,443		1,133		(17,743)		—
Noninterest expense	283,986		28,603		17,860		29,432		359,881

Income (loss) before income taxes	120,883		23,316		(1,482)		(33,571)		109,146
Income taxes	37,142		5,596		(393)		(7,711)		34,634
Net income	$	83,741	$	17,720	$	(1,089)	$	(25,860)	$	74,512


	Nine Months Ended September 30, 2024
(dollars in thousands)	Banking		Wealth Management		FirsTech		Other		Total
Interest income	$	392,336	$	—	$	—	$	29	$	392,365
Intersegment interest income	324		—		37		(361)		—
Interest expense	138,060		—		—		13,272		151,332
Intersegment interest expense	2,109		—		—		(2,109)		—
Net interest income	252,491		—		37		(11,495)		241,033
Provision for credit losses	6,677		—		—		—		6,677
Net interest income after provision for credit losses	245,814		—		37		(11,495)		234,356

Noninterest income
Wealth management fees	—		46,844		—		—		46,844
Payment technology solutions	—		—		16,889		—		16,889
Treasury management services	6,247		—		—		—		6,247
Card services and ATM fees	9,947		—		—		—		9,947
Other service charges on deposit accounts	7,059		—		—		—		7,059
All other noninterest income	15,414		1,145		(1)		917		17,475
Intersegment noninterest income	1,004		—		812		(1,816)		—
Noninterest income	39,671		47,989		17,700		(899)		104,461

Revenue	292,162		47,989		17,737		(12,394)		345,494

Noninterest expense
Salaries, wages, and employee benefits	87,358		19,831		7,277		15,695		130,161
Data processing	15,742		1,591		2,790		437		20,560
Amortization of intangible assets	6,705		881		—		—		7,586
Interchange expense	—		—		4,696		—		4,696
All other noninterest expense	49,954		2,079		1,822		6,014		59,869
Intersegment noninterest expense	8,605		2,322		1,081		(12,008)		—
Noninterest expense	168,364		26,704		17,666		10,138		222,872

Income (loss) before income taxes	117,121		21,285		71		(22,532)		115,945
Income taxes	30,711		5,108		18		(5,478)		30,359
Net income	$	86,410	$	16,177	$	53	$	(17,054)	$	85,586

- Definition

The entire disclosure for reporting segments including data and tables. Reportable segments include those that meet any of the following quantitative thresholds a) it's reported revenue, including sales to external customers and intersegment sales or transfers is 10 percent or more of the combined revenue, internal and external, of all operating segments b) the absolute amount of its reported profit or loss is 10 percent or more of the greater, in absolute amount of 1) the combined reported profit of all operating segments that did not report a loss or 2) the combined reported loss of all operating segments that did report a loss c) its assets are 10 percent or more of the combined assets of all operating segments.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 280
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-Name Accounting Standards Codification
-Section 50
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-Publisher FASB
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Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 280
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Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 280
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Reference 4: http://www.xbrl.org/2003/role/disclosureRef
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Reference 5: http://www.xbrl.org/2003/role/disclosureRef
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Reference 6: http://www.xbrl.org/2003/role/disclosureRef
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Reference 13: http://www.xbrl.org/2003/role/exampleRef
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Reference 14: http://www.xbrl.org/2003/role/exampleRef
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+ Details

ACCUMULATED OTHER COMPREHENSIVE INCOME (LOSS) (Tables)

9 Months Ended

Sep. 30, 2025

Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent, Alternative [Abstract]

Schedule of Accumulated Other Comprehensive Income (Loss)

The following tables present changes in AOCI by component, net of tax, for the periods indicated:


	Three Months Ended September 30, 2025
(dollars in thousands)	Unrealized Gains (Losses) on Debt Securities Available For Sale		Unrecognized Gains (Losses) on Debt Securities Held to Maturity		Unrealized Gains (Losses) on Cash Flow Hedges		Total
Balance, June 30, 2025	$	(125,745)	$	(20,198)	$	(9,368)	$	(155,311)
Unrealized holding gains (losses), net	16,326		—		(363)		15,963

Amounts reclassified from AOCI, net	1		—		1,721		1,722
Amortization of unrecognized losses on securities transferred to held to maturity	—		825		—		825
Balance, September 30, 2025	$	(109,418)	$	(19,373)	$	(8,010)	$	(136,801)


	Three Months Ended September 30, 2024
(dollars in thousands)	Unrealized Gains (Losses) on Debt Securities Available For Sale		Unrecognized Gains (Losses) on Debt Securities Held to Maturity		Unrealized Gains (Losses) on Cash Flow Hedges		Total
Balance, June 30, 2024	$	(176,246)	$	(23,464)	$	(20,616)	$	(220,326)
Unrealized holding gains (losses), net	39,286		—		7,439		46,725

Amounts reclassified from AOCI, net	8		—		1,690		1,698
Amortization of unrecognized losses on securities transferred to held to maturity	—		990		—		990
Balance, September 30, 2024	$	(136,952)	$	(22,474)	$	(11,487)	$	(170,913)


	Nine Months Ended September 30, 2025
(dollars in thousands)	Unrealized Gains (Losses) on Debt Securities Available For Sale		Unrecognized Gains (Losses) on Debt Securities Held to Maturity		Unrealized Gains (Losses) on Cash Flow Hedges		Total
Balance, December 31, 2024	$	(165,680)	$	(21,554)	$	(19,805)	$	(207,039)
Unrealized holding gains (losses), net	44,895		—		6,876		51,771

Amounts reclassified from AOCI, net	11,367		—		4,919		16,286
Amortization of unrecognized losses on securities transferred to held to maturity	—		2,181		—		2,181
Balance, September 30, 2025	$	(109,418)	$	(19,373)	$	(8,010)	$	(136,801)


	Nine Months Ended September 30, 2024
(dollars in thousands)	Unrealized Gains (Losses) on Debt Securities Available For Sale		Unrecognized Gains (Losses) on Debt Securities Held to Maturity		Unrealized Gains (Losses) on Cash Flow Hedges		Total
Balance, December 31, 2023	$	(176,636)	$	(25,473)	$	(16,694)	$	(218,803)
Unrealized holding gains (losses), net	34,810		—		211		35,021

Amounts reclassified from AOCI, net	4,874		—		4,996		9,870
Amortization of unrecognized losses on securities transferred to held to maturity	—		2,999		—		2,999
Balance, September 30, 2024	$	(136,952)	$	(22,474)	$	(11,487)	$	(170,913)

STOCK-BASED COMPENSATION - Schedule of Stock Appreciation Rights Activity (Details) - SSARs - USD ($) $ / shares in Units, $ in Thousands	9 Months Ended
	Sep. 30, 2025	Dec. 31, 2024
Shares
Outstanding at beginning of period (in shares)	0
Replacement of CrossFirst SSARs (in shares)	424,390
Exercised (in shares)	(119,842)
Forfeited (in shares)	(4,005)
Expired (in shares)	(30,145)
Outstanding at end of period (in shares)	270,398
Exercisable (in shares)	249,747
Weighted- Average Exercise Price
Outstanding at beginning of period (in dollars per share)	$ 0
Replacement of CrossFirst SSARs (in dollars per share)	15.78
Exercised (in dollars per shares)	13.31
Forfeited (in dollars per shares)	16.00
Expired (in dollars per shares)	23.23
Outstanding at ending of period (in dollars per share)	16.04
Exercisable (in dollars per share)	$ 15.62
Weighted- Average Remaining Contractual Term
Weighted- Average Remaining Contractual Term	5 years 2 months 23 days
Weighted- Average Remaining Contractual Term, Exercisable (in years)	5 years 2 months 1 day
Intrinsic value, options outstanding	$ 1,922	$ 0
Intrinsic value, exercisable at end of year	1,881
Aggregate intrinsic value of SSARs exercised	$ 1,100

LEASES

9 Months Ended

Sep. 30, 2025

Leases [Abstract]

LEASES

NOTE 5. LEASES

Busey as the Lessee

Busey’s leases consisting primarily of real estate leases for banking centers, ATM locations, and office space, as well as equipment leases. The following table summarizes lease-related balances that Busey reported on its Consolidated Balance Sheets (Unaudited):


		As of
(dollars in thousands)	Location	September 30, 2025		December 31, 2024
Lease balances
Right of use assets:
Operating leases	Other assets	$	29,236	$	10,608
Finance leases	Premises and equipment, net	5,235		—
Total right of use assets		$	34,471	$	10,608

Lease liabilities:
Operating leases	Other liabilities	$	31,592	$	11,040
Finance leases	Long-term borrowings	6,266		—
Total lease liabilities		$	37,858	$	11,040

Lease terms are summarized as follows:

As of

September 30,
2025

December 31,
2024

Lease terms

Weighted average remaining lease terms

Operating leases

7.28 years

7.55 years

Finance leases

16.51 years

N/A

Weighted average discount rates

Operating leases

4.22

3.77

Finance leases

5.10

N/A

The following table presents lease costs that Busey reported on its Consolidated Statements of Income (Unaudited):


		Three Months Ended September 30,				Nine Months Ended September 30,
(dollars in thousands)	Location	2025		2024		2025		2024
Lease costs
Operating lease costs:
Premises rent expense	Net occupancy expense of premises	$	1,483	$	604	$	4,221	$	1,692
Equipment rent expense	Furniture and equipment expenses	8		4		22		10
Finance lease costs:
Amortization expense	Net occupancy expense of premises	190		—		190		—
Interest expense	Long-term borrowings	187		—		187		—
Variable lease costs	Net occupancy expense of premises	15		15		45		43
Short-term lease costs	Net occupancy expense of premises	14		12		44		70
Total lease cost		$	1,897	$	635	$	4,709	$	1,815

Cash paid for amounts included in the measurement of lease liabilities was as follows:


	Three Months Ended September 30,				Nine Months Ended September 30,
(dollars in thousands)	2025		2024		2025		2024
Cash flows related to leases


Operating cash flows from operating leases	$	2,657	$	1,034	$	7,212	$	2,915
Operating cash flows from finance leases	187		—		187		—
Financing cash flows from finance leases	99		—		99		—

Right of use assets obtained in exchange for operating lease liabilities1	(6,331)		469		23,287		1,478
Right of use assets obtained in exchange for finance lease liabilities1	6,365		—		6,365		—

___________________________________________

Future undiscounted payments for leases with initial terms of one year or more, were as follows:


	As of September 30, 2025
(dollars in thousands)	Operating Leases		Finance Leases
Rent commitments
Remainder of 2025	$	1,618	$	123
2026	6,107		490
2027	5,623		527
2028	5,107		540
2029	4,110		540
2030	3,227		540
Thereafter	11,121		6,625
Total undiscounted cash flows	36,913		9,385
Less: Amounts representing interest	5,321		3,119
Present value of net future minimum lease payments	$	31,592	$	6,266

As of September 30, 2025, Busey had commitments totaling $6.0 million for two lease contracts with future accounting commencement dates.

Busey as the Lessor

Busey leases office and parking spaces to outside parties. Revenues recorded in connection with these leases, reported in other income on Busey’s Consolidated Statements of Income (Unaudited), are summarized as follows:


	Three Months Ended September 30,				Nine Months Ended September 30,
(dollars in thousands)	2025		2024		2025		2024
Rental income	$	214	$	206	$	647	$	612

Noncancellable terms for these leases, all of which are operating leases, extend through 2030. Under the terms of these lease agreements, Busey is entitled to receive aggregate future lease payments as shown in the table below:


(dollars in thousands)	As of September 30, 2025
Rents to be received
Remainder of 2025	$	211
2026	738
2027	515
2028	377
2029	197
2030	117

Total lease payments from operating leases	$	2,155

LEASES

NOTE 5. LEASES

Busey as the Lessee


		As of
(dollars in thousands)	Location	September 30, 2025		December 31, 2024
Lease balances
Right of use assets:
Operating leases	Other assets	$	29,236	$	10,608
Finance leases	Premises and equipment, net	5,235		—
Total right of use assets		$	34,471	$	10,608

Lease liabilities:
Operating leases	Other liabilities	$	31,592	$	11,040
Finance leases	Long-term borrowings	6,266		—
Total lease liabilities		$	37,858	$	11,040

Lease terms are summarized as follows:

As of

September 30,
2025

December 31,
2024

Lease terms

Weighted average remaining lease terms

Operating leases

7.28 years

7.55 years

Finance leases

16.51 years

N/A

Weighted average discount rates

Operating leases

4.22

3.77

Finance leases

5.10

N/A

The following table presents lease costs that Busey reported on its Consolidated Statements of Income (Unaudited):


		Three Months Ended September 30,				Nine Months Ended September 30,
(dollars in thousands)	Location	2025		2024		2025		2024
Lease costs
Operating lease costs:
Premises rent expense	Net occupancy expense of premises	$	1,483	$	604	$	4,221	$	1,692
Equipment rent expense	Furniture and equipment expenses	8		4		22		10
Finance lease costs:
Amortization expense	Net occupancy expense of premises	190		—		190		—
Interest expense	Long-term borrowings	187		—		187		—
Variable lease costs	Net occupancy expense of premises	15		15		45		43
Short-term lease costs	Net occupancy expense of premises	14		12		44		70
Total lease cost		$	1,897	$	635	$	4,709	$	1,815

Cash paid for amounts included in the measurement of lease liabilities was as follows:


	Three Months Ended September 30,				Nine Months Ended September 30,
(dollars in thousands)	2025		2024		2025		2024
Cash flows related to leases


Operating cash flows from operating leases	$	2,657	$	1,034	$	7,212	$	2,915
Operating cash flows from finance leases	187		—		187		—
Financing cash flows from finance leases	99		—		99		—

Right of use assets obtained in exchange for operating lease liabilities1	(6,331)		469		23,287		1,478
Right of use assets obtained in exchange for finance lease liabilities1	6,365		—		6,365		—

___________________________________________

Future undiscounted payments for leases with initial terms of one year or more, were as follows:


	As of September 30, 2025
(dollars in thousands)	Operating Leases		Finance Leases
Rent commitments
Remainder of 2025	$	1,618	$	123
2026	6,107		490
2027	5,623		527
2028	5,107		540
2029	4,110		540
2030	3,227		540
Thereafter	11,121		6,625
Total undiscounted cash flows	36,913		9,385
Less: Amounts representing interest	5,321		3,119
Present value of net future minimum lease payments	$	31,592	$	6,266

As of September 30, 2025, Busey had commitments totaling $6.0 million for two lease contracts with future accounting commencement dates.

Busey as the Lessor


	Three Months Ended September 30,				Nine Months Ended September 30,
(dollars in thousands)	2025		2024		2025		2024
Rental income	$	214	$	206	$	647	$	612


(dollars in thousands)	As of September 30, 2025
Rents to be received
Remainder of 2025	$	211
2026	738
2027	515
2028	377
2029	197
2030	117

Total lease payments from operating leases	$	2,155

EARNINGS PER COMMON SHARE (Tables)

9 Months Ended

Sep. 30, 2025

Earnings Per Share [Abstract]

Schedule of Computation of Earnings Per Common Share

Earnings per common share have been computed as follows:


	Three Months Ended September 30,				Nine Months Ended September 30,
(dollars in thousands, except per share amounts)	2025		2024		2025		2024
Net income	$	57,098	$	32,004	$	74,512	$	85,586
Dividends on preferred stock	(5,131)		—		(5,286)		—
Net income available to common stockholders	$	51,967	$	32,004	$	69,226	$	85,586

Weighted average number of common shares outstanding, basic	89,136,898		57,033,359		82,508,723		56,458,430
Dilutive effect of common stock equivalents:
Options	187		1,714		63		572

SSARs	204,106		—		191,460		—
RSU awards	815,829		655,224		817,169		662,609
PSU awards	32,510		254,365		65,031		264,451
DSU awards	17,204		16,766		15,656		18,390
ESPP	11,648		6,420		11,897		6,847
Weighted average number of common shares outstanding, diluted	90,218,382		57,967,848		83,609,999		57,411,299

Basic earnings per common share	$	0.58	$	0.56	$	0.84	$	1.52
Diluted earnings per common share	$	0.58	$	0.55	$	0.83	$	1.49

Schedule of Average Shares Excluded From Computation of Diluted Earnings Per Common Share

Shares that were excluded from the computation of diluted earnings per common share because their effect would have been anti-dilutive are summarized in the table below for the periods presented:


	Three Months Ended September 30,		Nine Months Ended September 30,
	2025	2024	2025	2024
Anti-dilutive common stock equivalents
Options	—	—	10,071	12,784


RSU awards	—	—	1,498	4,288
PSU awards	298,211	107,065	238,099	103,001


Total anti-dilutive common stock equivalents	298,211	107,065	249,668	120,073

MERGERS AND ACQUISITIONS - Schedule of Pre-tax Acquisition Expenses (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2025	Sep. 30, 2024	Sep. 30, 2025	Sep. 30, 2024
Business Combination [Line Items]
Pre-tax acquisition expenses	$ 7,251	$ 1,935	$ 95,449	$ 4,432
M&M
Business Combination [Line Items]
Pre-tax acquisition expenses	0	597	108	2,947
CrossFirst
Business Combination [Line Items]
Pre-tax acquisition expenses	$ 7,251	$ 1,338	95,341	$ 1,485
Adjustment to the initial provision for unfunded commitments			$ 4,000

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

+ Details

LEASES - Schedule of Lease-Related Balances (Details) - USD ($) $ in Thousands	Sep. 30, 2025	Dec. 31, 2024
Right of use assets:
Operating leases	$ 29,236	$ 10,608
Finance leases	5,235	0
Total right of use assets	34,471	10,608
Lease liabilities:
Operating leases	31,592	11,040
Finance leases	6,266	0
Total lease liabilities	$ 37,858	$ 11,040
Weighted average remaining lease terms
Operating leases	7 years 3 months 10 days	7 years 6 months 18 days
Finance leases	16 years 6 months 3 days
Weighted average discount rates
Operating leases	4.22%	3.77%
Finance leases	5.10%

BORROWINGS - Schedule of Securities Sold Under Agreements to Repurchase (Details) - USD ($) $ in Thousands	Sep. 30, 2025	Dec. 31, 2024
Debt Disclosure [Abstract]
Securities sold under agreements to repurchase	$ 147,152	$ 155,610
Weighted average rate for securities sold under agreements to repurchase	2.50%	2.63%

- Definition

Amount, after the effects of master netting arrangements, of funds outstanding borrowed in the form of a security repurchase agreement between the entity and another party for the sale and repurchase of identical or substantially the same securities at a date certain for a specified price. Includes liabilities not subject to a master netting arrangement and not elected to be offset.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 235
-SubTopic 10
-Name Accounting Standards Codification
-Section S50
-Paragraph 1
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480738/235-10-S50-1

Reference 2: http://www.xbrl.org/2003/role/exampleRef
-Topic 210
-SubTopic 20
-Name Accounting Standards Codification
-Section 55
-Paragraph 20
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147483444/210-20-55-20

Reference 3: http://www.xbrl.org/2003/role/exampleRef
-Topic 210
-SubTopic 20
-Name Accounting Standards Codification
-Section 55
-Paragraph 15
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147483444/210-20-55-15

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Topic 210
-SubTopic 20
-Name Accounting Standards Codification
-Section 55
-Paragraph 10
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147483444/210-20-55-10

Reference 5: http://www.xbrl.org/2003/role/disclosureRef
-Topic 210
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 3
-Subparagraph (c)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147483466/210-20-50-3

Reference 6: http://fasb.org/us-gaap/role/ref/legacyRef
-Topic 942
-SubTopic 210
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03(13)(1))
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147478546/942-210-S99-1

Reference 7: http://www.xbrl.org/2003/role/disclosureRef
-Topic 946
-SubTopic 320
-Name Accounting Standards Codification
-Section S99
-Paragraph 2
-Subparagraph (SX 210.12-12A(Column A)(Footnote 2))
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147477271/946-320-S99-2

Reference 8: http://www.xbrl.org/2003/role/disclosureRef
-Topic 946
-SubTopic 320
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.12-12(Column A)(Footnote 2))
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147477271/946-320-S99-1

Reference 9: http://www.xbrl.org/2003/role/disclosureRef
-Topic 946
-SubTopic 320
-Name Accounting Standards Codification
-Section S99
-Paragraph 6
-Subparagraph (SX 210.12-14(Column A)(Footnote 2))
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147477271/946-320-S99-6

Reference 10: http://www.xbrl.org/2003/role/disclosureRef
-Topic 946
-SubTopic 320
-Name Accounting Standards Codification
-Section S99
-Paragraph 3
-Subparagraph (SX 210.12-12B(Column A)(Footnote 4)(b))
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147477271/946-320-S99-3

Reference 11: http://www.xbrl.org/2003/role/disclosureRef
-Topic 235
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08(m)(1)(i))
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480678/235-10-S99-1

Reference 12: http://www.xbrl.org/2003/role/disclosureRef
-Topic 235
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08(m)(1)(ii)(A)(i))
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480678/235-10-S99-1

+ Details

FAIR VALUE MEASUREMENTS (Tables)

9 Months Ended

Sep. 30, 2025

Fair Value Disclosures [Abstract]

Schedule of Financial Assets and Financial Liabilities Measured at Fair Value on a Recurring Basis

The following tables summarize financial assets and financial liabilities measured at estimated fair value on a recurring basis:


	As of September 30, 2025
(dollars in thousands)	Level 1 Inputs		Level 2 Inputs		Level 3 Inputs		Total Fair Value
Debt securities available for sale:

Obligations of U.S. government corporations and agencies	$	—	$	113,605	$	—	$	113,605
Obligations of states and political subdivisions	—		247,544		—		247,544
Asset-backed securities	—		285,562		—		285,562
Commercial mortgage-backed securities	—		135,981		—		135,981
Residential mortgage-backed securities	—		1,267,576		—		1,267,576
Corporate debt securities	—		48,991		—		48,991
Equity securities	190		15,741		—		15,931
Derivative assets	—		33,934		39		33,973
Derivative liabilities	—		45,914		59		45,973


	As of December 31, 2024
(dollars in thousands)	Level 1 Inputs		Level 2 Inputs		Level 3 Inputs		Total Fair Value
Debt securities available for sale:

Obligations of U.S. government corporations and agencies	$	—	$	1,400	$	—	$	1,400
Obligations of states and political subdivisions	—		139,829		—		139,829
Asset-backed securities	—		336,557		—		336,557
Commercial mortgage-backed securities	—		92,174		—		92,174
Residential mortgage-backed securities	—		1,087,210		—		1,087,210
Corporate debt securities	—		153,051		—		153,051
Equity securities	5,567		10,295		—		15,862
Derivative assets	—		30,368		5		30,373
Derivative liabilities	—		58,099		—		58,099

Activity for risk participation agreements, which are financial assets measured at estimated fair value on a recurring basis using Level 3, is summarized in the table below:


		Three Months Ended September 30,				Nine Months Ended September 30,
(dollars in thousands)	Location	2025		2024		2025		2024
Beginning Balance		$	(45)	$	8	$	5	$	15
Gains (losses) recognized in earnings	Other expense	170		(5)		163		(15)

Purchases		(145)		13		(171)		16
Sales		—		—		24		—
Assumed in acquisition		—		—		(41)		—




Ending Balance		$	(20)	$	16	$	(20)	$	16

Schedule of Assets and Liabilities Measured at Fair Value on a Non-Recurring Basis

The following tables summarize financial assets and financial liabilities measured at estimated fair value on a non-recurring basis:


	As of September 30, 2025
(dollars in thousands)	Level 1 Inputs		Level 2 Inputs		Level 3 Inputs		Total Fair Value
Loans evaluated individually, net of related allowance	$	—	$	—	$	19,056	$	19,056
OREO and other repossessed assets with subsequent impairment	—		—		2,628		2,628
Bank property held for sale with impairment	—		—		2,099		2,099


	As of December 31, 2024
(dollars in thousands)	Level 1 Inputs		Level 2 Inputs		Level 3 Inputs		Total Fair Value
Loans evaluated individually, net of related allowance	$	—	$	—	$	616	$	616

Bank property held for sale with impairment	—		—		2,841		2,841

Schedule of Quantitative Information About Level 3 Fair Value Measurements

The following table presents additional quantitative information about assets measured at estimated fair value on a non-recurring basis using Level 3 inputs:

As of September 30, 2025

(dollars in thousands)

Fair Value

Valuation
Techniques

Unobservable
Input

Range
(Weighted Average)

Loans evaluated individually, net of related allowance

19,056

Appraisal of collateral

Appraisal adjustments

-1.6% to -100.0%

(-32.2)%

OREO and other repossessed assets with subsequent impairment

2,628

Appraisal of collateral

Appraisal adjustments

-6.6% to -24.1%

(-7.0)%

Bank property held for sale with impairment

2,099

Appraisal of collateral or real estate listing price

Appraisal adjustments

-9.0% to -86.8%

(-57.3)%

As of December 31, 2024

(dollars in thousands)

Fair Value

Valuation
Techniques

Unobservable
Input

Range
(Weighted Average)

Loans evaluated individually, net of related allowance

616

Appraisal of collateral

Appraisal adjustments

-25.0% to -100.0%

(-74.9)%

Bank property held for sale with impairment

2,841

Appraisal of collateral or real estate listing price

Appraisal adjustments

-9.0% to -76.7%

(-51.8)%

Schedule of Estimated Fair Values of Financial Instruments

Fair values of financial instruments that are not carried at fair value on Busey’s Consolidated Balance Sheets (Unaudited) were estimated as follows:


	As of September 30, 2025				As of December 31, 2024
(dollars in thousands)	Carrying Amount		Fair Value		Carrying Amount		Fair Value
Financial assets
Level 1 inputs:
Cash and cash equivalents	$	385,474	$	385,474	$	697,659	$	697,659
Level 2 inputs:
Debt securities held to maturity	784,821		659,471		826,630		675,053
Loans held for sale	8,943		8,993		3,657		3,726
Restricted bank stock	77,006		77,006		49,930		49,930
Accrued interest receivable	79,578		79,578		45,141		45,141
Level 3 inputs:
Portfolio loans, net	13,424,085		13,505,193		7,613,683		7,426,158
Mortgage servicing rights	1,441		5,260		1,304		5,627
Other servicing rights	2,274		2,315		1,482		1,591

Financial liabilities
Level 2 inputs:
Time deposits	$	2,433,788	$	2,428,428	$	1,490,635	$	1,481,591
Securities sold under agreements to repurchase	147,152		147,152		155,610		155,610

Long-term borrowings	92,431		92,452		—		—
Junior subordinated debt owed to unconsolidated trusts	77,257		71,478		74,815		67,314
Accrued interest payable	24,355		24,355		21,129		21,129
Level 3 inputs:

Subordinated notes, net of unamortized issuance costs	103,283		98,490		227,723		219,043

MERGERS AND ACQUISITIONS - Narrative (Details) $ / shares in Units, $ in Thousands				1 Months Ended	3 Months Ended	7 Months Ended
	Mar. 01, 2025 USD ($) state $ / shares shares	Feb. 28, 2025 USD ($)	Apr. 01, 2024 USD ($) $ / shares shares	Mar. 31, 2025 bankingCenter	Jun. 30, 2025 USD ($)	Sep. 30, 2025 USD ($)	Dec. 31, 2024 USD ($)
Business Combination, Contingent Consideration [Line Items]
Number of full-service locations \| bankingCenter				79
Number of states in which entity operates \| state	10
Preferred stock redemption price per share (in dollars per share) \| $ / shares	$ 1,000
Fair value adjustments						$ (1,800)
Goodwill						$ 383,323	$ 333,695
CrossFirst
Business Combination, Contingent Consideration [Line Items]
Total consideration paid	$ 808,980	$ 6,000
Goodwill	49,553
Fair value of financial assets acquired	4,700,000
Gross contractual amounts of acquired receivables	$ 4,790,000
CrossFirst \| Common \| CrossFirst \| SSARs
Business Combination, Contingent Consideration [Line Items]
Shares received for each share owned (in shares) \| shares	0.6675
M&M
Business Combination, Contingent Consideration [Line Items]
Shares received for each share owned (in shares) \| shares			5.7294
Total consideration paid			$ 49,575
Goodwill			$ 15,897
Per share cash consideration entitled, Cash Election (in dollars per share) \| $ / shares			$ 117.74
Consideration transferred per share in cash, Mixed Election (in dollars per share) \| $ / shares			$ 34.55
Mixed consideration (in shares) \| shares			4.0481
Business combination consideration, number of shares (in shares) \| shares			1,429,304
Cash			$ 12,200
Consideration transferred per share in cash, Share Election (in dollars per share) \| $ / shares			$ 5.3966
Consideration transferred per share in shares, Share Election (in shares) \| shares			5.4668
Cash consideration received (in dollars per share) \| $ / shares			$ 117.74
Fractional shares, payment rate (in dollars per share) \| $ / shares			$ 23.32
Additional consideration transferred			$ 3,000
Number of shares redeemed ( in shares) \| shares			300
Business acquisition fair value adjustment, deferred taxes					$ 100

STOCK-BASED COMPENSATION - Schedule of Stock-Based Compensation Expense (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2025	Sep. 30, 2024	Sep. 30, 2025	Sep. 30, 2024
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Total stock-based compensation expense	$ 4,298	$ 2,291	$ 13,125	$ 5,828
SSARs
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Total stock-based compensation expense	14	0	121	0
RSU Awards
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Total stock-based compensation expense	2,600	1,057	8,296	3,012
PSU Awards
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Total stock-based compensation expense	1,381	976	3,826	2,037
DSU Awards
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Total stock-based compensation expense	223	211	620	615
ESPP
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Total stock-based compensation expense	$ 80	$ 47	$ 262	$ 164

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

+ Details

DEBT SECURITIES - Schedule of Debt Securities in an Unrealized or Unrecognized Loss Position (Details) - USD ($) $ in Thousands	Sep. 30, 2025	Dec. 31, 2024
Fair Value
Less than 12 months	$ 182,678	$ 185,148
12 months or more	980,555	1,281,595
Total	1,163,233	1,466,743
Unrealized Losses
Less than 12 months	(2,650)	(895)
12 months or more	(159,575)	(229,430)
Total	(162,225)	(230,325)
Fair Value
12 months or more	659,471	675,053
Total	659,471	675,053
Unrecognized Losses
12 months or more	(125,350)	(151,577)
Total	(125,350)	(151,577)
Obligations of U.S. government corporations and agencies
Fair Value
Less than 12 months	69,984	0
12 months or more	0	1,328
Total	69,984	1,328
Unrealized Losses
Less than 12 months	(195)	0
12 months or more	0	(8)
Total	(195)	(8)
Obligations of states and political subdivisions
Fair Value
Less than 12 months	99,487	11,234
12 months or more	95,200	119,723
Total	194,687	130,957
Unrealized Losses
Less than 12 months	(2,375)	(209)
12 months or more	(10,206)	(16,527)
Total	(12,581)	(16,736)
Asset-backed securities
Fair Value
Less than 12 months		14,997
12 months or more		0
Total		14,997
Unrealized Losses
Less than 12 months		(3)
12 months or more		0
Total		(3)
Commercial mortgage-backed securities
Fair Value
Less than 12 months	5,813	6,238
12 months or more	72,141	85,936
Total	77,954	92,174
Unrealized Losses
Less than 12 months	(61)	(42)
12 months or more	(11,682)	(15,089)
Total	(11,743)	(15,131)
Fair Value
12 months or more	329,632	338,288
Total	329,632	338,288
Unrecognized Losses
12 months or more	(68,743)	(77,242)
Total	(68,743)	(77,242)
Residential mortgage-backed securities
Fair Value
Less than 12 months	1,427	152,081
12 months or more	782,258	930,642
Total	783,685	1,082,723
Unrealized Losses
Less than 12 months	(1)	(640)
12 months or more	(135,785)	(191,259)
Total	(135,786)	(191,899)
Fair Value
12 months or more	329,839	336,765
Total	329,839	336,765
Unrecognized Losses
12 months or more	(56,607)	(74,335)
Total	(56,607)	(74,335)
Corporate debt securities
Fair Value
Less than 12 months	5,967	598
12 months or more	30,956	143,966
Total	36,923	144,564
Unrealized Losses
Less than 12 months	(18)	(1)
12 months or more	(1,902)	(6,547)
Total	$ (1,920)	$ (6,548)

STOCK-BASED COMPENSATION - Schedule of Stock Appreciation Rights Valuation Assumptions (Details) - SSARs	9 Months Ended
	Sep. 30, 2025 $ / shares
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Expected volatility, minimum	29.10%
Expected volatility, maximum	36.70%
Expected dividends	4.17%
Risk-free rate, minimum	3.97%
Risk-free rate, maximum	4.03%
Weighted average grant date fair value per share (in dollars per share)	$ 8.94
Exercise timing, number of days after termination	90 days
Termination rate assumed thereafter (as a percent)	5.00%
Minimum
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Simulation term	4 years 2 months 12 days
Termination rate assumed (as a percent)	25.00%
Maximum
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Simulation term	5 years 8 months 8 days
Termination rate assumed (as a percent)	50.00%

PORTFOLIO LOANS - Schedule of Loan Modifications for Borrowers Experiencing Financial Difficulty (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2025	Sep. 30, 2024	Sep. 30, 2025	Sep. 30, 2024
Interest Rate Reduction
Loans identified as impaired
Amortized cost basis	$ 263		$ 263
% of total class of financing receivable	0.00%		0.00%
Interest Rate Reduction \| Commercial loans \| C&I and other commercial
Loans identified as impaired
Amortized cost basis	$ 263		$ 263
% of total class of financing receivable	0.00%		0.00%
Interest Rate Reduction \| Commercial loans \| CRE
Loans identified as impaired
Amortized cost basis	$ 0		$ 0
% of total class of financing receivable	0.00%		0.00%
Interest Rate Reduction \| Commercial loans \| Real estate construction
Loans identified as impaired
Amortized cost basis			$ 0
% of total class of financing receivable			0.00%
Payment Deferral
Loans identified as impaired
Amortized cost basis	$ 4,388	$ 325	$ 14,949	$ 325
% of total class of financing receivable	0.00%	0.00%	0.10%	0.00%
Payment Deferral \| Commercial loans \| C&I and other commercial
Loans identified as impaired
Amortized cost basis	$ 2,444	$ 325	$ 13,005	$ 325
% of total class of financing receivable	0.10%	0.00%	0.30%	0.00%
Payment Deferral \| Commercial loans \| CRE
Loans identified as impaired
Amortized cost basis	$ 1,944	$ 0	$ 1,944	$ 0
% of total class of financing receivable	0.00%	0.00%	0.00%	0.00%
Payment Deferral \| Commercial loans \| Real estate construction
Loans identified as impaired
Amortized cost basis		$ 0	$ 0	$ 0
% of total class of financing receivable		0.00%	0.00%	0.00%
Term Extension
Loans identified as impaired
Amortized cost basis	$ 10,878	$ 38,235	$ 28,302	$ 53,105
% of total class of financing receivable	0.10%	0.50%	0.20%	0.70%
Term Extension \| Commercial loans \| C&I and other commercial
Loans identified as impaired
Amortized cost basis	$ 10,417	$ 14,537	$ 22,314	$ 28,073
% of total class of financing receivable	0.20%	0.80%	0.50%	1.50%
Term Extension \| Commercial loans \| CRE
Loans identified as impaired
Amortized cost basis	$ 461	$ 18,448	$ 823	$ 19,782
% of total class of financing receivable	0.00%	0.50%	0.00%	0.60%
Term Extension \| Commercial loans \| Real estate construction
Loans identified as impaired
Amortized cost basis		$ 5,250	$ 5,165	$ 5,250
% of total class of financing receivable		1.30%	0.50%	1.30%

MERGERS AND ACQUISITIONS - Schedule of Pro Forma Information (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2025	Sep. 30, 2024	Sep. 30, 2025	Sep. 30, 2024
Business Combination, Asset Acquisition, Transaction between Entities under Common Control, and Joint Venture Formation [Abstract]
Revenue (net interest income plus noninterest income)	$ 191,142	$ 186,276	$ 562,462	$ 564,177
Net income	$ 55,120	$ 54,853	$ 123,822	$ 120,093

DERIVATIVE FINANCIAL INSTRUMENTS - Schedule of Financial Instruments Owned and Pledged as Collateral (Details) - USD ($) $ in Thousands	Sep. 30, 2025	Dec. 31, 2024
Cash pledged to secure obligations under derivative contracts
Derivative [Line Items]
Cash pledged to secure obligations	$ 14,400	$ 21,900
Collateral held to secure obligations under derivative contracts
Derivative [Line Items]
Cash pledged to secure obligations	$ 8,140	$ 20,260

- Definition

Amount of right to receive cash collateral under master netting arrangements that have not been offset against derivative liabilities.

+ References + Details

DERIVATIVE FINANCIAL INSTRUMENTS

9 Months Ended

Sep. 30, 2025

Derivative Instruments and Hedging Activities Disclosure [Abstract]

DERIVATIVE FINANCIAL INSTRUMENTS

NOTE 12. DERIVATIVE FINANCIAL INSTRUMENTS

Busey utilizes interest rate swap agreements as part of its asset liability management strategy to help manage its interest rate risk position. Additionally, Busey enters into derivative financial instruments, including interest rate lock commitments issued to residential loan customers for loans that will be held for sale; forward sales commitments to sell residential mortgage loans to investors; and interest rate swaps and risk participation agreements with customers and other third parties. See “Note 13: Fair Value Measurements” for further discussion of the fair value measurement of such derivatives.

To secure its obligations under derivative contracts, Busey pledged cash and held collateral as follows:


	As of
(dollars in thousands)	September 30, 2025		December 31, 2024
Cash pledged to secure obligations under derivative contracts	$	14,400	$	21,900
Collateral held to secure obligations under derivative contracts	8,140		20,260

Derivative Instruments Designated as Hedges

Busey entered into derivative instruments designated as cash flow hedges. For a derivative instrument that is designated and qualifies as a cash flow hedge, the change in fair value of the derivative instrument is reported as a component of OCI and reclassified into earnings in the same period or periods during which the hedged transaction affects earnings. Changes in fair value of components excluded from the assessment of effectiveness are recognized in current earnings.

Interest Rate Swaps Designated as Cash Flow Hedges

Interest rate swaps with notional amounts totaling $500.0 million as of both September 30, 2025, and December 31, 2024, were designated as cash flow hedges. Busey entered into a $300.0 million receive-fixed, pay-floating interest rate swap to reduce Busey’s asset sensitivity (Prime Loan Swap). Duration was added to Busey’s loan portfolio by fixing a portion of floating prime-based loans. Interest rates had risen above their historical lows allowing Busey to lock in a portion of its loan portfolio to reduce asset sensitivity while creating a more stable margin in a volatile rate market. These hedges were determined to be highly effective during the period, and Busey expects its hedges to remain highly effective during the remaining terms of the swaps. Further, Busey entered into forward-starting SOFR-based receive-fixed pay-floating interest rate swaps totaling $200.0 million to reduce Busey’s asset sensitivity (SOFR Loan Swaps). These hedges were determined to be highly effective during the period, and Busey expects its hedges to remain highly effective during the remaining terms of the swaps. Changes in the fair value of these interest rate swaps were recorded net of tax in OCI.

A summary of the interest-rate swaps designated as cash flow hedges is presented below:


		As of
(dollars in thousands)	Location	September 30, 2025			December 31, 2024
Prime Loan Swap
Notional amount		$	300,000		$	300,000
Weighted average rate: receive-fixed		4.81		%	4.81		%
Weighted average variable Prime pay rates		7.37		%	7.62		%
Weighted average maturity		3.35 years			4.10 years

SOFR Loan Swaps
Notional amount		$	200,000		$	200,000
Weighted average rate: receive-fixed		3.78		%	3.78		%
Weighted average variable 1-month CME Term SOFR pay rates		4.25		%	—
Weighted average maturity		4.01 years			4.76 years

Gross aggregate fair value of the swaps
Gross aggregate fair value of swap assets	Other assets	$	3,617		$	—
Gross aggregate fair value of swap liabilities	Other liabilities	15,670			27,770

Balances carried in AOCI
Unrealized gains (losses) on cash flow hedges, net of tax	AOCI	$	(8,010)		$	(19,805)


(dollars in thousands)	As of September 30, 2025

Unrealized gains (losses) expected to be reclassified from OCI to interest income	$	(716)

Interest income and interest expense recorded on these swap transactions is presented in the following table:


	Three Months Ended September 30,				Nine Months Ended September 30,
(dollars in thousands)	2025		2024		2025		2024
Interest on swap transactions
Increase (decrease) in interest income on swap transactions	$	(2,304)	$	(2,776)	$	(6,629)	$	(8,366)
(Increase) decrease in interest expense on swap transactions	—		412		—		1,378
Net increase (decrease) in net interest income on swap transactions	$	(2,304)	$	(2,364)	$	(6,629)	$	(6,988)

Net gains (losses) relating to cash flow derivative instruments that were recorded in OCI on the Consolidated Statements of Income (Unaudited) are presented in the table below:


	Three Months Ended September 30,				Nine Months Ended September 30,
(dollars in thousands)	2025		2024		2025		2024
Unrealized gains (losses) on cash flow hedges
Net gain (loss) recognized in OCI, net of tax	$	(363)	$	7,439	$	6,876	$	211
(Gain) loss reclassified from OCI to interest income, net of tax	1,721		1,984		4,919		5,981
(Gain) loss reclassified from OCI to interest expense, net of tax	—		(294)		—		(985)
Net change in unrealized gains (losses) on cash flow hedges, net of tax	$	1,358	$	9,129	$	11,795	$	5,207

Derivative Instruments Not Designated as Hedges

Interest Rate Swaps Not Designated as Hedges

Busey may offer derivative contracts to its customers in connection with their risk management needs. Busey manages the risk associated with these contracts by entering into equal and offsetting derivative agreements with third-party dealers. These contracts supported variable rate, commercial loan relationships totaling $1.01 billion as of September 30, 2025, and $719.2 million as of December 31, 2024. These derivatives generally worked together as an economic interest rate hedge, but Busey did not designate them for hedge accounting treatment. Consequently, changes in fair value of the corresponding derivative financial asset or liability were recorded as either a charge or credit to current earnings during the period in which the changes occurred.

Amounts and fair values of derivative assets and derivative liabilities related to customer interest rate swaps recorded on the Consolidated Balance Sheets (Unaudited) are summarized as follows:


		As of September 30, 2025				As of December 31, 2024
(dollars in thousands)	Location	Notional Amount		Fair Value		Notional Amount		Fair Value
Derivative assets not designated as hedging instruments
Interest rate swaps: receive-fixed, pay-floating	Other assets	$	521,477	$	10,746	$	156,539	$	1,465
Interest rate swaps: receive-floating, pay-fixed	Other assets	487,107		19,420		562,697		28,854
Derivative assets not designated as hedging instruments		$	1,008,584	$	30,166	$	719,236	$	30,319

Derivative liabilities not designated as hedging instruments
Interest rate swaps: receive-fixed, pay-floating	Other liabilities	$	487,107	$	19,420	$	562,697	$	28,854
Interest rate swaps: receive-floating, pay-fixed	Other liabilities	521,477		10,746		156,539		1,465
Derivative liabilities not designated as hedging instruments		$	1,008,584	$	30,166	$	719,236	$	30,319

Changes in fair value of these derivative assets and liabilities are included in the Consolidated Statements of Income (Unaudited) and are summarized as follows:


		Three Months Ended September 30,				Nine Months Ended September 30,
(dollars in thousands)	Location	2025		2024		2025		2024
Interest rate swaps
Receive-fixed, pay-floating	Noninterest expense	$	(1,083)	$	(9,224)	$	(21)	$	(3,050)
Receive-floating, pay-fixed	Noninterest expense	1,083		9,224		21		3,050
Net change in fair value of interest rate swaps		$	—	$	—	$	—	$	—

Risk Participation Agreements

To manage the credit risk exposure related to customer-facing swaps, Busey entered into risk participation agreements in conjunction with loan participation arrangements with other financial institutions. Under these risk participation agreements, Busey purchased credit risk participation, paying an up-front fee to a counterparty to accept a portion of its credit exposure, and will receive a payment from the counterparty if the swap customer defaults on its obligations. Busey also assumed additional risk participation agreements entered into by CrossFirst, in which CrossFirst purchased credit risk participation, and Busey will receive a payment from the counterparty if the swap customer defaults on its obligations.

In connection with the CrossFirst acquisition, Busey assumed risk participation agreements entered into by CrossFirst, under which CrossFirst sold credit risk participation, receiving an up-front fee from a counterparty in exchange for accepting a portion of the counterparty’s credit exposure. Under these agreements, Busey will be required to make a payment to the counterparty if the swap customer defaults on its obligations.

Notional amounts of the risk participation agreements reflect the participating banks’ pro-rata shares of the derivative instruments, consistent with their shares of the related participated loans. The risk participation agreements mature between October 2025 and August 2030, and are summarized as follows:


	As of
(dollars in thousands)	September 30, 2025		December 31, 2024
Risk participation agreements purchased
Number of risk participation agreements	12		5
Notional amount	$	73,919	$	40,092
Fair value	39		5

Risk participation agreements sold
Number of risk participation agreements	12		—
Notional amount	$	106,453	$	—
Fair value	59		—

Mortgage Banking Derivatives

Interest Rate Lock Commitments

Interest rate lock commitments that meet the definition of derivative financial instruments under ASC Topic 815 “Derivatives and Hedging” are carried at their fair values in other assets or other liabilities on the Consolidated Balance Sheets (Unaudited), with changes in the fair values of the corresponding derivative financial assets or liabilities recorded as either a charge or credit to current earnings during the period in which the changes occurred.

Forward Sales Commitments

Busey economically hedges mortgage loans held for sale and interest rate lock commitments issued to its residential loan customers related to loans that will be held for sale by obtaining corresponding forward sales commitments with an investor to sell the loans at an agreed-upon price at the time the interest rate locks are issued to the customers. Forward sales commitments that meet the definition of derivative financial instruments under ASC Topic 815 “Derivatives and Hedging” are carried at their fair values in other assets or other liabilities on the Consolidated Balance Sheets (Unaudited). While such forward sales commitments generally served as an economic hedge to mortgage loans held for sale and interest rate lock commitments, Busey did not designate them for hedge accounting treatment. Changes in fair value of the corresponding derivative financial asset or liability were recorded as either a charge or credit to current earnings during the period in which the changes occurred.

Amounts and fair values of mortgage banking derivatives included on the Consolidated Balance Sheets (Unaudited) are summarized as follows:


		As of September 30, 2025				As of December 31, 2024
(dollars in thousands)	Location	Notional Amount		Fair Value		Notional Amount		Fair Value
Mortgage banking derivative assets
Interest rate lock commitments	Other assets	$	6,515	$	132	$	2,430	$	28
Forward sales commitments	Other assets	4,679		19		3,457		21
Mortgage banking derivative assets		$	11,194	$	151	$	5,887	$	49

Mortgage banking derivative liabilities
Interest rate lock commitments	Other liabilities	$	—	$	—	$	436	$	4
Forward sales commitments	Other liabilities	9,290		78		1,955		6
Mortgage banking derivative liabilities		$	9,290	$	78	$	2,391	$	10

Gains and losses relating to these derivative instruments are reported in noninterest income, and are summarized as follows for the periods presented:


		Three Months Ended September 30,				Nine Months Ended September 30,
(dollars in thousands)	Location	2025		2024		2025		2024
Net gains (losses) on mortgage banking derivatives
Gains (losses) on interest rate lock commitments	Mortgage revenue	$	177	$	121	$	658	$	569
Gains (losses) on forward sales commitments	Mortgage revenue	(14)		(91)		(75)		(165)


Net gains (losses) on mortgage banking derivatives		$	163	$	30	$	583	$	404

- Definition

The entire disclosure for derivative instruments and hedging activities including, but not limited to, risk management strategies, non-hedging derivative instruments, assets, liabilities, revenue and expenses, and methodologies and assumptions used in determining the amounts.

+ References

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+ Details

CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (Unaudited) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2025	Sep. 30, 2024	Sep. 30, 2025	Sep. 30, 2024
Statement of Comprehensive Income [Abstract]
Net income	$ 57,098	$ 32,004	$ 74,512	$ 85,586
Unrealized/Unrecognized gains (losses) on debt securities:
Net unrealized holding gains (losses) on debt securities available for sale	24,391	54,950	61,710	48,688
Reclassification adjustment for realized (gains) losses on debt securities available for sale included in net income	13	11	15,549	6,817
Amortization of unrecognized losses on securities transferred to held to maturity	1,104	1,384	3,369	4,194
Tax effect	(8,356)	(16,061)	(22,185)	(17,016)
Net change in unrealized/unrecognized gains (losses) on debt securities	17,152	40,284	58,443	42,683
Unrealized gains (losses) on cash flow hedges:
Net unrealized holding gains (losses) on cash flow hedges	(486)	10,404	9,075	295
Reclassification adjustment for realized (gains) losses on cash flow hedges included in net income	2,304	2,364	6,629	6,988
Tax effect	(460)	(3,639)	(3,909)	(2,076)
Net change in unrealized gains (losses) on cash flow hedges	1,358	9,129	11,795	5,207
OCI	18,510	49,413	70,238	47,890
Total comprehensive income	$ 75,608	$ 81,417	$ 144,750	$ 133,476

DEPOSITS (Tables)

9 Months Ended

Sep. 30, 2025

Deposits [Abstract]

Schedule of Composition of Deposits

The composition of Busey’s deposits is presented in the table below:


	As of
(dollars in thousands)	September 30, 2025		December 31, 2024
Deposits
Noninterest-bearing demand deposits	$	3,554,936	$	2,719,907
Interest-bearing transaction deposits	3,171,255		2,423,237
Saving deposits and money market deposits	5,910,183		3,348,711
Time deposits	2,433,788		1,490,635
Total deposits	$	15,070,162	$	9,982,490

Additional information about Busey’s deposits is presented in the table below:


	As of
(dollars in thousands)	September 30, 2025		December 31, 2024
Brokered interest-bearing transaction deposits	$	50,240	$	—
Brokered savings deposits and money market deposits	10,000		6,002
Brokered time deposits	65,192		7,088
Aggregate amount of time deposits with a minimum denomination of $100,000	1,621,232		860,193
Aggregate amount of time deposits with a minimum denomination that meets or exceeds the FDIC insurance limit of $250,000	807,378		334,503

Schedule of Maturities of Time Deposits

Scheduled maturities of time deposits are presented in the table below:


(dollars in thousands)	As of September 30, 2025
Time deposits by schedule of maturities
Remainder of 2025	$	860,688
2026	1,531,369
2027	23,194
2028	10,487
2029	5,218
2030	2,409
Thereafter	423
Time deposits	$	2,433,788

CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY (Unaudited) (Parenthetical) - $ / shares	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2025	Sep. 30, 2024	Sep. 30, 2025	Sep. 30, 2024	Dec. 31, 2023
Statement of Stockholders' Equity [Abstract]
Cash dividends, common stock (in dollars per share)	$ 0.25	$ 0.24	$ 0.75	$ 0.72
Accounting Standards Update [Extensible Enumeration]					Accounting Standards Update 2023-02 [Member]

- Definition

Indicates amendment to accounting standards.

+ References

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+ Details

STOCK-BASED COMPENSATION

9 Months Ended

Sep. 30, 2025

Share-Based Payment Arrangement [Abstract]

STOCK-BASED COMPENSATION

NOTE 10. STOCK-BASED COMPENSATION

CrossFirst Acquisition

The CrossFirst acquisition impacted Busey and CrossFirst equity awards:

Treatment of Busey’s Equity Awards

Following the closing of the CrossFirst acquisition, except as otherwise provided in the CrossFirst Merger Agreement, Busey equity awards generally remain outstanding and subject to the same terms and conditions as applied immediately prior to the time at which the CrossFirst acquisition became effective (the “effective time”). Notable changes to Busey’s equity awards are as follows:

•ROATCE PSUs — Each PSU issued by Busey that is earned based on Core Return on Average Tangible Common Equity (the “ROATCE PSUs”) and was outstanding immediately prior to the effective time was deemed earned with the achievement of the applicable performance goals based on actual performance through December 31, 2024, the latest practicable date prior to the effective time, and otherwise remains subject to the same terms and conditions (including service-based vesting terms) as applied to such ROATCE PSUs immediately prior to the effective time. The ROATCE PSUs have been deemed earned (i) at 100% of the target level of performance, for the ROATCE PSUs granted in 2023 and (ii) at 75% of the target level of performance, for the ROATCE PSUs granted in 2024.

•TSR PSUs — Each Busey PSU previously granted that is tied to total stockholder return (“TSR”, and such PSUs, the “TSR PSUs”) with a performance period that ended December 31, 2024, (excluding TSR PSUs previously held by retirees) was replaced, and each TSR PSU outstanding immediately prior to the effective time with performance periods ending December 31, 2025, and December 31, 2026, (including existing TSR PSUs held by retirees) was modified, each effective March 1, 2025, such that the resulting new or modified PSUs (collectively, the “Merger PSUs”) will be earned based on Busey’s relative TSR rank as compared to the KBW Regional Banking Index, measured at the end of a performance period commencing January 1, 2025, and ending December 31, 2026. The Merger PSUs are subject to the terms and conditions of Busey’s Amended 2020 Equity Incentive Plan and the applicable award agreements. The target number of PSUs subject to each such Merger PSU was determined based on the number of PSUs that would have been earned in respect of the corresponding TSR PSU had performance for such corresponding TSR PSU been determined based on actual performance as of August 26, 2024, the day immediately prior to the announcement of the Merger, which is (i) in the case of the 2022 TSR PSUs, 94.5% of the original target level of performance, (ii) in the case of the 2023 TSR PSUs, 96.2% of the original target level of performance, and (iii) in the case of the 2024 TSR PSUs, 76.9% of the original target level of performance. Such target number also reflects the number of dividend equivalents accrued in respect of the corresponding existing TSR PSU that would have been earned based on the same actual TSR performance.

•Busey RSUs — Each outstanding Busey time-based restricted stock unit award (the “Busey RSUs”) will vest in equal annual installments over three (3) years following the effective time; provided that if any Busey RSU would otherwise vest by its terms on an earlier date, any then-unvested portion as of such date shall vest on such original vesting date.

Each Busey equity award will be subject to double-trigger vesting upon an involuntary termination within twelve (12) months following the effective time (at target performance, in the case of Merger PSUs).

Treatment of CrossFirst’s Equity Awards

Equity awards based on CrossFirst Common Stock that were outstanding immediately prior to the effective time were converted, at the effective time, either to Busey Common Stock or to equity awards based on Busey Common Stock, as follows:

•Director equity awards — Each CrossFirst restricted stock award held by a CrossFirst non-employee director and each deferred share of CrossFirst Common Stock that was credited to a director participant’s account under the CrossFirst 2018 Directors’ Deferred Fee Plan was converted into the right to receive 0.6675 shares of Busey Common Stock (the “Exchange Ratio”).

•CrossFirst RSUs — Each CrossFirst time-based restricted stock unit award (“CrossFirst RSU”) was converted into a restricted stock unit in respect of Busey Common Stock (a “Busey RSU”) based on the Exchange Ratio, rounded to the nearest whole share, subject to the same terms and conditions as were applicable to the CrossFirst RSUs prior to the effective time.

•CrossFirst PSUs — Each CrossFirst performance-based restricted stock unit award (“CrossFirst PSU”) was converted into a time-based Busey RSU based on the Exchange Ratio, subject to the same terms and conditions as were applicable to the CrossFirst PSUs prior to the effective time, assuming the achievement of the applicable performance goals based on, for the CrossFirst PSUs granted in 2023, actual performance through December 31, 2024, and, for the CrossFirst PSUs granted in 2024, target performance, rounded to the nearest whole share.

•CrossFirst SSARs — Each CrossFirst SSAR was converted into a stock appreciation right in respect of Busey Common Stock based on the Exchange Ratio, rounded down to the nearest whole share (and exercise price rounded up to the nearest cent), generally subject to the same terms and conditions as were applicable to the CrossFirst SSAR prior to the effective time.

Stock Options

Busey has outstanding stock options assumed from a 2017 acquisition. A summary of the status of, and changes in, Busey's stock option awards for the nine months ended September 30, 2025, follows:


Options	Shares	Weighted- Average Exercise Price		Weighted- Average Remaining Contractual Term	Intrinsic Value ($000's)
Outstanding at December 31, 2024	15,106	$	23.53	1.87 years	$	1



Outstanding at September 30, 2025	15,106	23.53		1.13 years	—

Exercisable at September 30, 2025	15,106	23.53		1.13 years	—

Stock Settled Appreciation Rights

Busey issued replacement awards in the form of SSARs as part of the acquisition of CrossFirst. These awards were issued under the CrossFirst Bankshares 2018 Omnibus Equity Incentive Plan with exercise prices equal to the closing price of CrossFirst’s common shares on the original date for each award adjusted by the Exchange Ratio of 0.6675, rounded up to the nearest cent. At grant, SSARs typically vested ratably over seven years of continuous service with a ten-year or fifteen-year contractual term. At grant, replacement SSARs had a weighted average remaining contractual term of 5.4 years, and unvested replacement SSARs had a weighted average remaining vesting period of 3.2 years. The fair value of each SSAR was estimated at acquisition date using a Monte Carlo simulation since the awards were all in-the-money. The fair value of SSARs that have vested during 2025 was $3.6 million.

A summary of SSAR activity during 2025 is presented below:


SSARs	Shares	Weighted- Average Exercise Price		Weighted- Average Remaining Contractual Term	Intrinsic Value ($000's)
Outstanding at December 31, 2024	—	$	—	—	$	—
Replacement of CrossFirst SSARs	424,390	15.78
Exercised1	(119,842)	13.31
Forfeited	(4,005)	16.00
Expired	(30,145)	23.23
Outstanding at September 30, 2025	270,398	16.04		5.23 years	1,922

Exercisable at September 30, 2025	249,747	15.62		5.17 years	1,881

___________________________________________

1. The aggregate intrinsic value of SSARs exercised during 2025 was $1.1 million.


(dollars in thousands, except per share amounts)	Nine Months Ended September 30, 2025
Assumptions
Expected volatility1	29.10% – 36.70%
Expected dividends2	4.17%
Simulation term3, 4, 5	4.20 years – 5.69 years
Risk-free rate6	3.97% – 4.03%
Weighted average grant date fair value per share	$	8.94

___________________________________________

1.Expected volatility was calculated using a historical volatility of Busey’s stock price over a period commensurate with the simulation term of the SSARs.

2.The dividend yield was calculated using Busey’s annual dividend and closing stock price on the date of acquisition.

3.The simulation term was commensurate with the midpoint of the longest expected term across all SSARs and was impacted by expected exercise behavior and termination rate.

5.As a component of determining the simulation term, termination rate was assumed to be between 25% and 50% in the first year following the acquisition and 5% for every year thereafter.

6.The risk-free rate for the simulation term of the SSARs was based on the continuously compounded semi-annual zero-coupon U.S. Treasury rates.

2020 Equity Plan

Busey has granted RSU, PSU, and DSU awards under the terms of its 2020 Equity Plan. Upon vesting and delivery, shares are expected, though not required, to be issued from treasury stock. There were 685,515 shares available for issuance under the 2020 Equity Plan as of September 30, 2025.

A description of RSU, PSU, and DSU awards granted in 2025 under the terms of the 2020 Equity Plan is provided below. Further information related to awards granted in prior years has been presented in the Annual Reports previously filed with the SEC corresponding to the year of each award grant.

RSU Awards

Busey grants RSU awards to members of management periodically throughout the year. RSU awards are stock-based awards for which vesting is conditional upon meeting established service criteria. Each RSU represents the future right to receive one share of Busey’s common stock. Recipients earn quarterly dividend equivalents on their respective RSUs, which entitle the recipients to additional units. Therefore, dividends earned each quarter compound based upon the updated unit balances.

On March 26, 2025, under the terms of the 2020 Equity Plan, Busey granted 348,269 RSUs to members of management. The grant date fair value of the award was $7.7 million, which will be recognized as compensation expense over the requisite service period. These awards will vest in equal installments on each of the first three anniversaries of the grant date. The terms of these awards included an accelerated vesting provision upon eligible retirement from Busey, after a one-year minimum requisite service period.

On May 29, 2025, under the terms of the 2020 Equity Plan, Busey granted 4,494 RSUs to members of management. The grant date fair value of the award was $0.1 million, which will be recognized as compensation expense over the requisite service period. These awards will vest in equal installments on each of the first three anniversaries of the grant date.

On July 23, 2025, under the terms of the 2020 Equity Plan, Busey granted 13,724 RSUs to members of management. The grant date fair value of the award was $0.3 million, which will be recognized as compensation expense over the requisite service period. These awards will vest on July 23, 2028.

A summary of changes in Busey’s RSU awards for the nine months ended September 30, 2025, is as follows:


RSU Awards	Shares	Weighted- Average Grant Date Fair Value
Nonvested at December 31, 2024	1,066,772	$	21.80
Conversion of Busey ROATCE PSUs to RSUs	157,094	23.99
Replacement of CrossFirst RSUs and PSUs	341,048	23.99
Granted	366,487	22.22
Dividend equivalents earned	48,060	22.30
Vested	(451,041)	20.03
Forfeited	(133,212)	22.38
Nonvested at September 30, 2025	1,395,208	23.23

PSU Awards

Busey grants PSU awards to members of management periodically throughout the year. PSU awards are stock-based awards for which vesting is conditional upon meeting established performance criteria for the applicable performance period and providing continuous service through the end of such performance period. Each PSU represents the future right to receive one share of Busey’s common stock. The number of PSUs that ultimately vest will be determined based on the extent to which the established performance criteria are achieved. Busey’s PSUs are subject to accelerated service-based vesting conditions upon eligible retirement from Busey. After performance determination, dividend equivalents are compounded based upon the updated PSU balances at each dividend date during the performance period.

On March 1, 2025, under the terms of the 2020 Equity Plan, in connection with the CrossFirst acquisition, Busey granted a target of 59,471 Merger PSUs to replace the 2022 TSR PSUs with a maximum award of 95,154 units. The actual number of units issued at the vesting date could range from 0% to 160% of the initial grant, depending on attaining a relative total stockholder return performance goal. The grant date fair value of the award, calculated using the Geometric Brownian Motion Model, is $1.3 million, which will be recognized in compensation expense over the performance period ending December 31, 2026.

On March 26, 2025, under the terms of the 2020 Equity Plan, Busey granted a target of 174,126 PSUs with a maximum award of 278,602 units. The actual number of units issued at the vesting date could range from 0% to 160% of the initial grant, depending on attaining a relative total stockholder return performance goal. The grant date fair value of the award, calculated using the Geometric Brownian Motion Model, is $3.4 million, which will be recognized in compensation expense over the performance period ending December 31, 2027.

On March 26, 2025, under the terms of the 2020 Equity Plan, Busey granted a target of 174,126 PSUs with a maximum award of 278,602 units. The actual number of units issued at the vesting date could range from 0% to 160% of the initial grant, depending on attaining an adjusted return on average tangible common equity performance goal. The grant date fair value of the award was $3.9 million, which will be recognized in compensation expense over the performance period ending December 31, 2027. The actual amount of compensation expense recognized for these awards is subject to adjustment based on the extent to which performance goals are expected to be achieved.

A summary of changes in Busey’s PSU awards for the nine months ended September 30, 2025, is as follows:


PSU Awards	Shares1	Weighted- Average Grant Date Fair Value
Nonvested at December 31, 2024	372,042	$	21.15
Modifications based on CrossFirst acquisition2	(181,828)	20.43
Granted	407,723	20.99
Dividend equivalents earned	125	20.83
Vested	(6,131)	20.87
Forfeited	(45,878)	20.95

Nonvested at September 30, 2025	546,053	21.29

___________________________________________

1.Shares for PSU awards represent target shares at the grant date.

2.Modifications include PSUs that were converted to RSUs as well as balance adjustments related to the 2023 TSR PSUs and the 2024 TSR PSUs.

DSU Awards

Busey grants DSU awards to its non-employee directors. DSU awards are stock-based awards with a deferred settlement date. Each DSU represents the future right to receive one share of Busey’s common stock. DSUs vest over a one-year period following the grant date. Under the 2020 Equity Plan, DSUs are generally subject to the same terms as RSUs, except that following vesting of DSUs, settlement occurs within 30 days following the earlier of separation from the board or a change in control of the Company. After vesting and prior to delivery, DSUs will continue to earn dividend equivalents.

On March 26, 2025, under the terms of the 2020 Equity Plan, Busey granted 39,846 DSUs to non-employee directors. The grant date fair value of the award totaled $0.9 million and will be recognized as compensation expense over the requisite service period of one year. Subsequent to the requisite service period, the awards will become 100% vested.

A summary of changes in Busey’s DSU awards for the nine months ended September 30, 2025, is as follows:


DSU Awards	Shares	Weighted- Average Grant Date Fair Value
Nonvested at December 31, 2024	36,893	$	23.40
Granted	39,846	22.16
Dividend equivalents earned	6,447	22.73
Vested	(42,424)	23.33

Nonvested at September 30, 2025	40,762	22.15

Vested and outstanding at September 30, 2025	144,461	23.01

Employee Stock Purchase Plan

The ESPP initially reserved for issuance and purchase an aggregate of 600,000 shares of Busey’s common stock. The first offering under the ESPP began on July 1, 2021. There were 314,203 shares available for issuance under the ESPP as of September 30, 2025.

Stock-based Compensation Expense

Busey recognized compensation expense related to non-vested equity awards as summarized in the table below:


		Three Months Ended September 30,				Nine Months Ended September 30,
(dollars in thousands)	Location	2025		2024		2025		2024
Stock-based compensation expense

SSARs	Salaries, wages, and employee benefits	$	14	$	—	$	121	$	—
RSU awards	Salaries, wages, and employee benefits	2,600		1,057		8,296		3,012
PSU awards1	Salaries, wages, and employee benefits	1,381		976		3,826		2,037
DSU awards	Other expense	223		211		620		615
ESPP	Salaries, wages, and employee benefits	80		47		262		164
Total stock-based compensation expense		$	4,298	$	2,291	$	13,125	$	5,828

___________________________________________

As all outstanding stock options were fully vested, no compensation expense was recorded for stock options for the three or nine months ended September 30, 2025, or 2024, and no unrecognized compensation expense remains for Busey’s stock option awards as of September 30, 2025.

Unamortized compensation expense related to non-vested equity awards is summarized in the table below:


	As of
(dollars in thousands)	September 30, 2025		December 31, 2024
Unamortized stock-based compensation
SSARs	$	114	$	—
RSU awards	11,402		7,093
PSU awards1	7,146		3,043
DSU awards	428		181
Total unamortized stock-based compensation	$	19,090	$	10,317

Weighted average period over which expense is to be recognized on awards issued under Busey's 2020 Equity Plan	1.9 years		2.5 years
Weighted average period over which expense is to be recognized on CrossFirst replacement awards	1.3 years		—

___________________________________________

LEASES - Schedule of Revenue Recorded in Connection with Leases (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2025	Sep. 30, 2024	Sep. 30, 2025	Sep. 30, 2024
Leases [Abstract]
Rental income	$ 214	$ 206	$ 647	$ 612

BORROWINGS - Subordinated Notes (Details) - Subordinated Debt - USD ($) $ in Millions	Apr. 01, 2024	Jun. 02, 2022	Jun. 01, 2020	Sep. 30, 2025
5.25% Notes Maturing June 1, 2030
Debt Instrument [Line Items]
Principal balance			$ 125.0
Interest rate			5.25%
Duration of fixed interest rate			5 years
Floating interest rate margin (as a percent)			5.11%
5.000% Notes Maturing June 15, 2032
Debt Instrument [Line Items]
Principal balance		$ 100.0
Interest rate		5.00%
Floating interest rate margin (as a percent)		2.52%
Percentage of principal amount of notes		100.00%
Debt Instrument, Variable Interest Rate, Type [Extensible Enumeration]		Secured Overnight Financing Rate (SOFR) [Member]
5.25% Notes Maturing December 4, 2030 \| M&M
Debt Instrument [Line Items]
Principal balance	$ 4.0
Floating interest rate margin (as a percent)	4.97%
Debt Instrument, Variable Interest Rate, Type [Extensible Enumeration]	Secured Overnight Financing Rate (SOFR) [Member]
Fixed to floating interest rate (as a percent)	5.25%
Fair value discount outstanding				$ 0.0

LEASES - Narrative (Details) $ in Millions	Sep. 30, 2025 USD ($) lease
Leases [Abstract]
Leases not yet commenced commitments \| $	$ 6.0
Number of leases not yet commenced \| lease	2

PORTFOLIO LOANS - Schedule of Financial Instruments Owned and Pledged as Collateral (Details) - USD ($) $ in Thousands	Sep. 30, 2025	Dec. 31, 2024
Financial Instruments Owned and Pledged as Collateral [Line Items]
Pledged loans	$ 13,424,085	$ 7,613,683
Total pledged loans
Financial Instruments Owned and Pledged as Collateral [Line Items]
Pledged loans	6,992,439	5,579,424
FHLB
Financial Instruments Owned and Pledged as Collateral [Line Items]
Pledged loans	5,018,506	4,813,600
Federal Reserve Bank
Financial Instruments Owned and Pledged as Collateral [Line Items]
Pledged loans	$ 1,973,933	$ 765,824

REGULATORY CAPITAL - Narrative (Details)	Sep. 30, 2025
Banking and Thrift, Other Disclosure [Abstract]
Common equity Tier 1 capital to risk-weighted assets of at least 7.0%, basis points exceeded	0.0533
Tier 1 capital to risk-weighted assets of at least 8.5%, basis points exceeded	0.0527
Total capital to risk-weighted assets of at least 10.5%, basis points exceeded	0.0539

SIGNIFICANT ACCOUNTING POLICIES

9 Months Ended

Sep. 30, 2025

Accounting Policies [Abstract]

SIGNIFICANT ACCOUNTING POLICIES

NOTE 1. SIGNIFICANT ACCOUNTING POLICIES

Nature of Operations

First Busey Corporation, a Nevada corporation organized in 1980, is an $18.19 billion financial holding company headquartered in Leawood, Kansas. Busey’s common stock is traded on The Nasdaq Global Select Market under the symbol “BUSE” and Busey’s depositary shares, each representing a 1/40th interest in a share of Busey Series B Preferred Stock, are traded under the symbol “BUSEP.”

Busey operates and reports its business in three segments: Banking, Wealth Management, and FirsTech.

•The Banking operating segment provides a full range of banking services to individual and corporate customers through its banking center network in Arizona, Colorado, Florida, Illinois, Indiana, Kansas, Missouri, New Mexico, Oklahoma, and Texas.

•The Wealth Management operating segment provides a full range of asset management, investment, brokerage, fiduciary, philanthropic advisory, tax preparation, and farm management services to individuals, businesses, and foundations.

•The FirsTech operating segment provides comprehensive and innovative payment technology solutions including online, mobile, and voice-recognition bill payments; money management and credit card networks; direct debit services; lockbox remittance processing for payments made by mail; and walk-in payments. FirsTech also provides additional tools to help clients with billing, reconciliation, bill reminders, and treasury services.

For additional information about Busey's operating segments, see “Note 16. Operating Segments and Related Information.”

Busey conducts its Banking and Wealth Management services through Busey Bank, and provides payment technology solutions through Busey Bank’s wholly owned subsidiary, FirsTech. Busey also has various other subsidiaries that are not significant to the consolidated entity.

Basis of Financial Statement Presentation

These unaudited consolidated financial statements and related notes should be read together with the audited consolidated financial statements included in Busey's 2024 Annual Report. These interim unaudited consolidated financial statements serve to update Busey’s 2024 Annual Report and may not include all information and notes necessary to constitute a complete set of financial statements.

Busey’s unaudited consolidated financial statements are prepared in conformity with GAAP, and reflect the elimination of intercompany accounts and transactions. Certain prior year amounts have been reclassified to conform to the current period presentation. These reclassifications did not have a material impact on Busey’s consolidated financial condition or results of operations.

In the opinion of Busey’s management, the unaudited consolidated financial statements reflect all normal, recurring adjustments needed to present fairly Busey’s results for the interim periods. The results of operations for interim periods are not necessarily indicative of the results that may be expected for the full year or any other interim period.

Use of Estimates

In preparing the accompanying unaudited consolidated financial statements in conformity with GAAP, Busey’s management is required to make estimates and assumptions that affect the amounts reported in the financial statements and the disclosures provided. Actual results could differ from those estimates. Critical accounting estimates which are particularly susceptible to significant change in the near term relate to the fair value of assets acquired and liabilities assumed in business combinations, goodwill, income taxes, and the determination of the ACL.

Cash and Cash Equivalents

Cash and cash equivalents include cash on hand, cash items in process of collection, amounts due from other banks, and interest-bearing deposits held with other financial institutions. The carrying amount of these instruments is considered a reasonable estimate of fair value. At September 30, 2025, cash and cash equivalents included $13.6 million contractually restricted by a third-party service provider, $14.4 million pledged to secure obligations under derivative contracts, and $68.1 million of reserved cash subject to call by the Federal Reserve Bank, as a member of the Federal Reserve System.

Leases

A determination is made at inception if an arrangement contains a lease. For arrangements containing leases, Busey classifies the lease as either operating, finance, or short-term. Busey recognizes operating and finance leases as right of use assets and corresponding lease liabilities. Right of use assets are recognized on the lease commencement date at amounts equal to the respective lease liabilities, adjusted for prepaid lease payments, initial direct costs, and lease incentives received. Lease liabilities are recognized at the present value of the remaining contractual fixed lease payments, discounted using the rate implicit in the lease or Busey’s incremental borrowing rate.

ASC Topic 842 “Leases” requires the use of the rate implicit in the lease whenever this rate is readily determinable. If not readily determinable, Busey uses its incremental borrowing rate at lease inception, on a collateralized basis, over a similar term. For operating leases existing prior to Busey’s adoption of ASC Topic 842 on January 1, 2019, Busey used a borrowing rate that corresponded to the lease term remaining as of the date of adoption of ASC Topic 842.

Busey’s lease agreements often include one or more options to renew at Busey’s discretion. When Busey considers the exercise of a renewal option to be reasonably certain, contractual fixed lease payments for the renewal term are included in the calculation of the right of use asset and lease liability.

Right of use assets are reviewed for impairment in accordance with Busey’s policies regarding long-lived assets.

Operating Leases

Right of use assets for operating leases are included in other assets on the Consolidated Balance Sheets (Unaudited). Lease liabilities for operating leases are included in other liabilities on the Consolidated Balance Sheets (Unaudited).

Lease costs for operating leases are recognized on a straight-line basis over the lease term. Lease costs are reflected as noninterest expense for net occupancy of premises or for furniture and equipment expenses, as appropriate, on the Consolidated Statements of Income (Unaudited). Variable lease payments are expensed as incurred.

Finance Leases

Right of use assets for finance leases and the related accumulated amortization are included in premises and equipment, net, on the Consolidated Balance Sheets (Unaudited). Lease liabilities for finance leases are included in long-term borrowings on the Consolidated Balance Sheets (Unaudited). Repayments of the principal portion of finance lease liabilities are reflected as financing activities on the Consolidated Statements of Cash Flows (Unaudited).

Lease costs for finance leases are composed of interest expense and amortization expense. Interest expense on finance leases is reflected as interest expense on long-term borrowings on the Consolidated Statements of Income (Unaudited). Amortization expense on finance leases is reflected as noninterest expense for net occupancy of premises on the Consolidated Statements of Income (Unaudited).

Busey had one finance lease as of September 30, 2025, which was acquired through its acquisition of CrossFirst.

Short-term Leases

Leases with terms of twelve months or less are classified as short-term leases. Busey made an accounting policy election to not recognize short-term leases on the balance sheet. Lease costs for short-term leases are reflected as noninterest expense for net occupancy of premises or for furniture and equipment expenses, as appropriate, on the Consolidated Statements of Income (Unaudited).

For additional information about Busey’s leases, see “Note 5. Leases.”

Income Taxes

Busey is subject to income taxes in U.S. federal and various state jurisdictions. First Busey Corporation and its subsidiaries file consolidated federal and state income tax returns with each subsidiary computing its taxes on a separate entity basis. Tax regulations within each jurisdiction are subject to the interpretation of the related tax laws and regulations, which requires significant judgment.

On July 4, 2025, new federal tax legislation commonly referred to as the “One Big Beautiful Bill Act” (the “OBBBA”) was enacted, which made permanent many of the tax provisions of the 2017 Tax Cuts and Jobs Act that were set to expire in 2025 and introduced several significant amendments to federal tax legislation. Key provisions of the OBBBA include the restoration of immediate expensing of domestic research and development expenditures, reinstatement of 100% bonus depreciation, more favorable rules for determining the limitation on business interest expense, and incentives for financial institutions to increase lending in rural and agricultural communities. The effects of the legislation were reflected in the unaudited consolidated financial statements for the period ending September 30, 2025, and did not have a material impact on our results of operations. Busey will continue evaluating the impact of this legislation for future reporting periods.

As of September 30, 2025, Busey Bank was under examination by the Florida Department of Revenue for its 2020 to 2022 corporate income tax filings. Busey Bank accrued $0.1 million related to potential assessment adjustments and interest. Busey had no accruals for payments of interest and penalties related to uncertain tax positions at September 30, 2025 or 2024.

As of September 30, 2025, Busey was also under examination by the Illinois Department of Revenue for M&M’s tax filings for the tax years ended December 31, 2022 and 2023.

Preferred Stock

On March 1, 2025, in connection with the CrossFirst acquisition, Busey issued 7,750 shares of Busey Series A Preferred Stock, which were issued to holders of shares of CrossFirst Series A Non-Cumulative Perpetual Preferred Stock. The Busey Series A Preferred Stock bears a dividend rate of 8.00% per annum on the liquidation preference of $1,000 per share. Dividend payments commenced on June 13, 2025. The Busey Series A Preferred Stock is not subject to any mandatory redemption, sinking fund, or similar provision. Busey may redeem the Busey Series A Preferred Stock, in whole or in part, on or after March 1, 2030, subject to the approval of the appropriate federal banking agency, at a redemption price of $1,000 per share, plus any declared and unpaid dividends, without accumulation of any undeclared dividends, to, but excluding, the date of redemption. Additional information about the Busey Series A Preferred Stock can be found in Busey’s Form 8-K filed with the SEC on August 27, 2024, and the Agreement and Plan of Merger, dated August 26, 2024, by and between First Busey Corporation and CrossFirst Bankshares, Inc. filed therewith.

On May 20, 2025, Busey issued 8,600,000 depositary shares (the “Depositary Shares,”), which are traded on The Nasdaq Global Select Market under the symbol “BUSEP.” Each Depositary Share represents a 1/40th interest in a share of Busey Series B Preferred Stock. The Series B Preferred Stock has a liquidation preference of $1,000 per share (equivalent to $25 per Depositary Share). Dividend payments for the Series B Preferred Stock commenced on September 1, 2025. The Series B Preferred Stock is not subject to any mandatory redemption, sinking fund, or similar provision. Busey may redeem the Series B Preferred Stock, in whole or in part, at its option, on any dividend payment date on or after June 1, 2030, subject to the approval of the appropriate federal banking agency, at a redemption price of $1,000 per share (equivalent to $25 per Depositary Share) plus any declared and unpaid dividends to, but excluding, the date of redemption. Additional information about the Depositary Shares and the Series B Preferred Stock can be found in Busey’s Form 8-K filed with the SEC on May 20, 2025, and the exhibits filed therewith.

The following tables summarize Busey’s preferred stock issuances:


	September 30, 2025
Title of Eash Issue	Shares Authorized	Shares Issued	Shares Outstanding	Balance		Per Share Preference in Liquidation		Aggregate Liquidation Preference ($ in 000's)

Preferred stock, $0.001 par value:	1,000,000
Series A Non-Cumulative Perpetual Preferred Stock	7,750	7,750	7,750	$	7.75	$	1,000.00	$	7,750
8.25% Fixed-Rate Series B Non-Cumulative Perpetual Preferred Stock	230,000	215,000	215,000	$	215.00	$	1,000.00	$	215,000

Changes in preferred stock issued are presented in the following table:


	Three Months Ended September 30,				Nine Months Ended September 30,
Title of Eash Issue	2025		2024		2025		2024


Series A Non-Cumulative Perpetual Preferred Stock	$	—	$	—	$	7.75	$	—
8.25% Fixed-Rate Series B Non-Cumulative Perpetual Preferred Stock	—		—		215.00		—

Impact of Recently Adopted Accounting Standards

In March 2024, the FASB issued ASU 2024-01 “Compensation-Stock Compensation (Topic 718): Scope Application of Profits Interest and Similar Awards” to clarify that certain “profits interests” are within the scope of Topic 718 by amending the language and providing illustrative examples on how the scope guidance in paragraph 718-10-15-3 should be applied. This update is intended to improve clarity of the accounting standards codification, not to change the guidance. This update was adopted on a prospective basis for annual and interim reporting periods beginning January 1, 2025. Busey does not currently have any Profit Interest and Similar Awards, so adoption of this ASU did not have any impact on its financial position or results of operations.

In November 2023, the FASB issued ASU 2023‑07 “Segment Reporting (Topic 820): Improvements to Reportable Segment Disclosures” requiring enhanced disclosures related to significant segment expenses. This standard was adopted on a retrospective basis beginning with the annual reporting period ending December 31, 2024, and for interim reporting periods within fiscal years starting January 1, 2025. Adoption of this standard did not have a material impact on Busey’s financial position or results of operations, but resulted in enhanced disclosures.

Recently Issued Accounting Standards Not Yet Adopted

In September 2025, the FASB issued ASU 2025-07 “Derivatives and Hedging (Topic 815) and Revenue from Contracts with Customers (Topic 606): Derivatives Scope Refinements and Scope Clarification for Share-Based Noncash Consideration from a Customer in a Revenue Contract,” to reduce diversity in the application of derivative accounting practices. This update provides a scope limitation on the definition of a derivative subject to derivative accounting under ASC Topic 815, Derivatives and Hedging, to exclude certain non-exchange-traded contracts with contingencies based on operations or activities specific to one of the parties to the contract. In addition, this update clarifies that share-based noncash consideration from a customer that is contingent on the satisfaction of performance obligations should not be recognized at contract inception as a derivative asset or an equity security, but rather should be accounted for under the guidance in ASC Topic 606, Revenue from Contracts with Customers, and that guidance in other topics does not apply to share-based noncash consideration from a customer for the transfer of goods or services unless or until the entity’s right to receive or retain the share-based noncash consideration is unconditional under ASC Topic 606. The amendments in this update may be applied on either a prospective or modified retrospective basis, and will be effective for Busey for annual and interim reporting periods beginning January 1, 2027. Early adoption is permitted. Busey is currently evaluating the effect this ASU may have on its financial position and results of operations.

In September 2025, the FASB issued ASU 2025-06 “Intangibles—Goodwill and Other—Internal-Use Software (Subtopic 350-40): Targeted Improvements to the Accounting for Internal-Use Software,” changing the criteria for capitalizing software costs to the following: (1) a commitment has been made to fund the software project, and (2) it is probable the project will be competed and used to perform its intended function. Under this update, software development stages are no longer a consideration in the determination of which costs are capitalized. The amendments in this update may be adopted on a prospective, modified transition, or retrospective basis, and will be effective for Busey for annual and interim reporting periods beginning January 1, 2028. Early adoption is permitted. Busey is currently evaluating the effect this ASU may have on its financial position and results of operations.

In July 2025, the FASB issued ASU 2025-05 “Financial Instruments—Credit Losses (Topic 326): Measurement of Credit Losses for Accounts Receivable and Contract Assets,” providing a practical expedient which, if elected, permits an entity to assume that current conditions as of the balance sheet date will remain static for the remaining life of the assets, removing the requirement to consider reasonable, supportable forecasts. The amendments in this update are to be applied prospectively, and will be effective for Busey for annual and interim reporting periods beginning January 1, 2026. Early adoption is permitted. Busey is currently evaluating the effect this ASU may have on its financial position and results of operations.

In November 2024, the FASB issued ASU 2024-04 “Debt—Debt with Conversion and Other Options (Subtopic 470-20): Induced Conversions of Convertible Debt Instruments” to clarify when certain settlements of convertible debt instruments should be accounted for as an induced conversion. The amendments in this update may be applied on either a prospective or retrospective basis and will be effective for Busey for annual and interim reporting periods beginning January 1, 2026. Because Busey does not currently have any convertible debt, the Company does not expect adoption of this ASU to have any impact on its financial position or results of operations.

In November 2024, the FASB issued ASU 2024-03 “Income Statement—Reporting Comprehensive Income—Expense Disaggregation Disclosures (Subtopic 220-40): Disaggregation of Income Statement Expenses” to require additional disclosures within the notes to the financial statements about certain expense items. Specifically, disaggregation of income statement captions that contain expenses within the following five categories is required: (1) purchases of inventory, (2) employee compensation, (3) depreciation, (4) intangible asset amortization, and (5) depreciation, depletion, and amortization (“DD&A”) costs recognized as part of oil- and gas-producing activities or other amounts of depletion expense. Further, this update requires disclosure of the total amount of selling expenses and the entity’s definition of selling expenses. This update provides a practical expedient for banks and bank holding companies to continue presenting salaries and employee benefits in conformity with SEC Rule 210.9-04 instead of requiring those entities to apply the employee compensation definition included in Subtopic 220-40. The amendments in this update may be applied on either a prospective or retrospective basis and will be effective for Busey beginning with the annual reporting period ending December 31, 2027, and interim reporting periods beginning January 1, 2028. Early adoption is permitted. Because this update relates only to disclosure, Busey does not expect adoption of this ASU to have any impact on its financial position or results of operations.

In December 2023, the FASB issued ASU 2023‑09 “Income Taxes (Topic 740): Improvements to Income Tax Disclosures,” which requires more detailed disclosures of income taxes paid net of refunds received, income from continuing operations before income tax expense or benefit, and income tax expense from continuing operations. This standard is to be applied on a prospective basis, with retrospective application permitted, and will be effective for Busey for annual reporting periods beginning with the fiscal year ending December 31, 2025. Busey does not expect adoption of this ASU to have a material impact on its financial position or results of operations.

In October 2023, the FASB issued ASU 2023‑06 “Disclosure Improvements: Codification Amendments in Response to the SEC’s Disclosure Update and Simplification Initiative” which aligns certain GAAP disclosure requirements with the SEC’s disclosure requirements, in order to better facilitate comparisons between entities that are subject to the SEC’s existing disclosures with entities that were not previously subject to the SEC’s requirements. Amendments in this update should be applied prospectively, and the effective date for Busey for each amendment in this ASU will be the date on which the SEC removes the related disclosure from Regulation S‑X or Regulation S‑K. Early adoption is prohibited. If the SEC has not removed the related disclosures from Regulation S‑X or Regulation S‑K by June 30, 2027, the pending content of this update will be removed from the ASC and will not become effective for any entity. Busey does not expect adoption of this ASU to have a material impact on its financial position or results of operations.

Subsequent Events

Busey has evaluated subsequent events for potential recognition and/or disclosure through the date the unaudited consolidated financial statements included in this Quarterly Report were issued. Subsequent to quarter end, on October 24, 2025, Busey issued a conditional notice of full redemption of its $4.0 million 5.25% Subordinated Note maturing December 4, 2030, which was acquired on April 1, 2024, in connection with the acquisition of M&M. The redemption of the Subordinated Note is subject to and conditioned upon regulatory approval from the Federal Reserve. Assuming the requisite approvals are obtained, the Subordinated Note will be redeemed on its optional redemption date of December 4, 2025. Other than this event, there were no significant events subsequent to the quarter ended September 30, 2025, through the filing date of these unaudited consolidated financial statements.

FAIR VALUE MEASUREMENTS - Schedule of Financial Assets and Financial Liabilities Measured at Fair Value on a Recurring Basis (Details) - USD ($) $ in Thousands	Sep. 30, 2025	Dec. 31, 2024
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt securities available for sale	$ 2,099,259	$ 1,810,221
Equity securities	15,931	15,862
Obligations of U.S. government corporations and agencies
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt securities available for sale	113,605	1,400
Obligations of states and political subdivisions
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt securities available for sale	247,544	139,829
Asset-backed securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt securities available for sale	285,562	336,557
Commercial mortgage-backed securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt securities available for sale	135,981	92,174
Residential mortgage-backed securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt securities available for sale	1,267,576	1,087,210
Corporate debt securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt securities available for sale	48,991	153,051
Fair Value, Recurring \| Derivative assets
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets	33,973	30,373
Fair Value, Recurring \| Derivative liabilities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative liabilities	45,973	58,099
Fair Value, Recurring \| Obligations of U.S. government corporations and agencies
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt securities available for sale	113,605	1,400
Fair Value, Recurring \| Obligations of states and political subdivisions
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt securities available for sale	247,544	139,829
Fair Value, Recurring \| Asset-backed securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt securities available for sale	285,562	336,557
Fair Value, Recurring \| Commercial mortgage-backed securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt securities available for sale	135,981	92,174
Fair Value, Recurring \| Residential mortgage-backed securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt securities available for sale	1,267,576	1,087,210
Fair Value, Recurring \| Corporate debt securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt securities available for sale	48,991	153,051
Fair Value, Recurring \| Equity securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equity securities	15,931	15,862
Fair Value, Recurring \| Level 1 Inputs \| Derivative assets
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets	0	0
Fair Value, Recurring \| Level 1 Inputs \| Derivative liabilities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative liabilities	0	0
Fair Value, Recurring \| Level 1 Inputs \| Obligations of U.S. government corporations and agencies
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt securities available for sale	0	0
Fair Value, Recurring \| Level 1 Inputs \| Obligations of states and political subdivisions
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt securities available for sale	0	0
Fair Value, Recurring \| Level 1 Inputs \| Asset-backed securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt securities available for sale	0	0
Fair Value, Recurring \| Level 1 Inputs \| Commercial mortgage-backed securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt securities available for sale	0	0
Fair Value, Recurring \| Level 1 Inputs \| Residential mortgage-backed securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt securities available for sale	0	0
Fair Value, Recurring \| Level 1 Inputs \| Corporate debt securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt securities available for sale	0	0
Fair Value, Recurring \| Level 1 Inputs \| Equity securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equity securities	190	5,567
Fair Value, Recurring \| Level 2 Inputs \| Derivative assets
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets	33,934	30,368
Fair Value, Recurring \| Level 2 Inputs \| Derivative liabilities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative liabilities	45,914	58,099
Fair Value, Recurring \| Level 2 Inputs \| Obligations of U.S. government corporations and agencies
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt securities available for sale	113,605	1,400
Fair Value, Recurring \| Level 2 Inputs \| Obligations of states and political subdivisions
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt securities available for sale	247,544	139,829
Fair Value, Recurring \| Level 2 Inputs \| Asset-backed securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt securities available for sale	285,562	336,557
Fair Value, Recurring \| Level 2 Inputs \| Commercial mortgage-backed securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt securities available for sale	135,981	92,174
Fair Value, Recurring \| Level 2 Inputs \| Residential mortgage-backed securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt securities available for sale	1,267,576	1,087,210
Fair Value, Recurring \| Level 2 Inputs \| Corporate debt securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt securities available for sale	48,991	153,051
Fair Value, Recurring \| Level 2 Inputs \| Equity securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equity securities	15,741	10,295
Fair Value, Recurring \| Level 3 Inputs \| Derivative assets
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets	39	5
Fair Value, Recurring \| Level 3 Inputs \| Derivative liabilities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative liabilities	59	0
Fair Value, Recurring \| Level 3 Inputs \| Obligations of U.S. government corporations and agencies
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt securities available for sale	0	0
Fair Value, Recurring \| Level 3 Inputs \| Obligations of states and political subdivisions
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt securities available for sale	0	0
Fair Value, Recurring \| Level 3 Inputs \| Asset-backed securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt securities available for sale	0	0
Fair Value, Recurring \| Level 3 Inputs \| Commercial mortgage-backed securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt securities available for sale	0	0
Fair Value, Recurring \| Level 3 Inputs \| Residential mortgage-backed securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt securities available for sale	0	0
Fair Value, Recurring \| Level 3 Inputs \| Corporate debt securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Debt securities available for sale	0	0
Fair Value, Recurring \| Level 3 Inputs \| Equity securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equity securities	$ 0	$ 0

PORTFOLIO LOANS - Schedule of Activity on the Allowance for Loan Losses (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2025	Sep. 30, 2024	Sep. 30, 2025	Sep. 30, 2024
Activity in the allowance for loan losses
ACL beginning balance	$ 183,334	$ 85,226	$ 83,404	$ 91,740
Day 1 PCD				1,243
Day 2 Provision for Credit Losses	(3,305)		50,308	6,677
Provision for loan losses		2	(2,281)	7,317
Charged-off	(7,448)	(674)	(52,666)	(16,410)
Recoveries	1,600	427	2,508	1,091
ACL ending balance	174,181	84,981	174,181	84,981
CrossFirst
Activity in the allowance for loan losses
Day 1 PCD			100,783
Day 2 Provision for Credit Losses			42,433
Commercial loans \| C&I and other commercial
Activity in the allowance for loan losses
ACL beginning balance	68,578	20,286	21,589	21,256
Day 1 PCD				824
Day 2 Provision for Credit Losses	(4,768)
Provision for loan losses		715	(23,008)	13,958
Charged-off	(5,753)	(202)	(39,054)	(15,433)
Recoveries	1,379	210	1,692	404
ACL ending balance	59,436	21,009	59,436	21,009
Commercial loans \| C&I and other commercial \| CrossFirst
Activity in the allowance for loan losses
Day 1 PCD			75,569
Day 2 Provision for Credit Losses			22,648
Commercial loans \| CRE
Activity in the allowance for loan losses
ACL beginning balance	70,935	35,104	32,301	35,465
Day 1 PCD				322
Day 2 Provision for Credit Losses	1,323
Provision for loan losses		(1,158)	14,300	(1,882)
Charged-off	(1,438)	(215)	(12,607)	(315)
Recoveries	24	4	158	145
ACL ending balance	70,844	33,735	70,844	33,735
Commercial loans \| CRE \| CrossFirst
Activity in the allowance for loan losses
Day 1 PCD			21,588
Day 2 Provision for Credit Losses			15,104
Commercial loans \| Real estate construction
Activity in the allowance for loan losses
ACL beginning balance	13,072	3,722	3,345	5,163
Day 1 PCD				0
Day 2 Provision for Credit Losses	(880)
Provision for loan losses		39	3,731	(1,449)
Charged-off	0	0	0	0
Recoveries	1	10	94	57
ACL ending balance	12,193	3,771	12,193	3,771
Commercial loans \| Real estate construction \| CrossFirst
Activity in the allowance for loan losses
Day 1 PCD			2,112
Day 2 Provision for Credit Losses			2,911
Retail loans \| CRE
Activity in the allowance for loan losses
ACL beginning balance	29,042	23,729	23,711	26,298
Day 1 PCD				96
Day 2 Provision for Credit Losses	739
Provision for loan losses		120	2,833	(2,624)
Charged-off	(53)	(32)	(172)	(159)
Recoveries	115	162	413	368
ACL ending balance	29,843	23,979	29,843	23,979
Retail loans \| CRE \| CrossFirst
Activity in the allowance for loan losses
Day 1 PCD			1,430
Day 2 Provision for Credit Losses			1,628
Retail loans \| Retail other
Activity in the allowance for loan losses
ACL beginning balance	1,707	2,385	2,458	3,558
Day 1 PCD				1
Day 2 Provision for Credit Losses	281
Provision for loan losses		286	(137)	(686)
Charged-off	(204)	(225)	(833)	(503)
Recoveries	81	41	151	117
ACL ending balance	$ 1,865	$ 2,487	1,865	$ 2,487
Retail loans \| Retail other \| CrossFirst
Activity in the allowance for loan losses
Day 1 PCD			84
Day 2 Provision for Credit Losses			$ 142

TAX CREDIT INVESTMENTS AND OTHER INVESTMENTS IN UNCONSOLIDATED ENTITIES (Tables)

9 Months Ended

Sep. 30, 2025

Investments, All Other Investments [Abstract]

Schedule of Investments


		As of
(dollars in thousands)	Location	September 30, 2025		December 31, 2024
Investments in unconsolidated entities
Funded investments	Other assets	$	90,776	$	70,796
Unfunded investments	Other assets	47,659		61,210
Investments in unconsolidated entities		$	138,435	$	132,006

Unfunded investment obligations	Other liabilities	$	47,659	$	61,210

Actual amounts of income tax credits and other benefits, along with the investment amortization, are presented in the table below:


	Three Months Ended September 30,				Nine Months Ended September 30,
(dollars in thousands)	2025		2024		2025		2024
Income tax credits and other tax benefits	$	4,446	$	4,040	$	13,354	$	11,941
Amortization of investments in tax-advantaged projects	3,968		3,575		11,905		10,593

CONSOLIDATED STATEMENTS OF INCOME (Unaudited) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2025	Sep. 30, 2024	Sep. 30, 2025	Sep. 30, 2024
Interest income
Interest and fees on loans	$ 214,357	$ 111,336	$ 568,299	$ 320,302
Taxable interest income	22,146	17,789	63,836	56,264
Non-taxable interest income	1,644	283	3,926	918
Dividend income on bank stock	871	106	2,173	291
Other interest income	5,487	5,092	20,532	14,590
Total interest income	244,505	134,606	658,766	392,365
Interest expense
Deposits	84,611	46,634	230,070	134,311
Federal funds purchased and securities sold under agreements to repurchase	976	981	2,738	3,393
Short-term borrowings	26	26	589	676
Long-term borrowings	937	0	1,967	300
Subordinated notes	1,417	3,181	7,203	9,467
Junior subordinated debt owed to unconsolidated trusts	1,401	1,137	4,148	3,185
Total interest expense	89,368	51,959	246,715	151,332
Net interest income	155,137	82,647	412,051	241,033
Provision for credit losses	(985)	409	50,308	6,677
Net interest income after provision for credit losses	156,122	82,238	361,743	234,356
Noninterest income
Mortgage revenue	657	355	1,762	1,579
Income on bank owned life insurance	1,623	1,189	4,814	4,050
Realized net gains (losses) on the sale of mortgage servicing rights	0	(18)	0	7,724
Realized net gains (losses) on securities	(13)	(11)	(15,549)	(6,817)
Unrealized net gains (losses) recognized on equity securities	(275)	833	5,490	911
Other noninterest income	5,916	4,706	13,674	10,028
Total noninterest income	41,198	35,845	107,284	104,461
Noninterest expense
Salaries, wages, and employee benefits	74,145	44,593	220,068	130,161
Data processing	9,714	6,910	33,310	20,560
Net occupancy expense of premises	7,982	4,633	21,613	13,943
Furniture and equipment expenses	2,143	1,647	6,296	5,155
Professional fees	2,931	3,118	15,316	7,866
Amortization of intangible assets	4,507	2,548	12,182	7,586
Interchange expense	1,336	1,352	3,976	4,696
FDIC insurance	3,151	1,413	7,742	4,273
Other noninterest expense	14,109	9,305	39,378	28,632
Total noninterest expense	120,018	75,519	359,881	222,872
Income before income taxes	77,302	42,564	109,146	115,945
Income taxes	20,204	10,560	34,634	30,359
Net income	57,098	32,004	74,512	85,586
Dividends on preferred stock	5,131	0	5,286	0
Net income available to common stockholders	$ 51,967	$ 32,004	$ 69,226	$ 85,586
Weighted average number of common shares outstanding, basic (in shares)	89,136,898	57,033,359	82,508,723	56,458,430
Weighted average number of common shares outstanding, diluted (in shares)	90,218,382	57,967,848	83,609,999	57,411,299
Basic earnings per common share (in dollars per share)	$ 0.58	$ 0.56	$ 0.84	$ 1.52
Diluted earnings per common share (in dollars per share)	$ 0.58	$ 0.55	$ 0.83	$ 1.49
Wealth management fees
Noninterest income
Noninterest income	$ 17,184	$ 15,378	$ 51,325	$ 46,844
Payment technology solutions
Noninterest income
Noninterest income	5,092	5,265	15,121	16,889
Treasury management services
Noninterest income
Noninterest income	4,598	2,201	12,596	6,247
Card services and ATM fees
Noninterest income
Noninterest income	4,799	3,557	13,388	9,947
Other service charges on deposit accounts
Noninterest income
Noninterest income	$ 1,617	$ 2,390	$ 4,663	$ 7,059

ACCUMULATED OTHER COMPREHENSIVE INCOME (LOSS)

9 Months Ended

Sep. 30, 2025

Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent, Alternative [Abstract]

ACCUMULATED OTHER COMPREHENSIVE INCOME (LOSS)

NOTE 15. ACCUMULATED OTHER COMPREHENSIVE INCOME (LOSS)

The following tables present changes in AOCI by component, net of tax, for the periods indicated:


	Three Months Ended September 30, 2025
(dollars in thousands)	Unrealized Gains (Losses) on Debt Securities Available For Sale		Unrecognized Gains (Losses) on Debt Securities Held to Maturity		Unrealized Gains (Losses) on Cash Flow Hedges		Total
Balance, June 30, 2025	$	(125,745)	$	(20,198)	$	(9,368)	$	(155,311)
Unrealized holding gains (losses), net	16,326		—		(363)		15,963

Amounts reclassified from AOCI, net	1		—		1,721		1,722
Amortization of unrecognized losses on securities transferred to held to maturity	—		825		—		825
Balance, September 30, 2025	$	(109,418)	$	(19,373)	$	(8,010)	$	(136,801)


	Three Months Ended September 30, 2024
(dollars in thousands)	Unrealized Gains (Losses) on Debt Securities Available For Sale		Unrecognized Gains (Losses) on Debt Securities Held to Maturity		Unrealized Gains (Losses) on Cash Flow Hedges		Total
Balance, June 30, 2024	$	(176,246)	$	(23,464)	$	(20,616)	$	(220,326)
Unrealized holding gains (losses), net	39,286		—		7,439		46,725

Amounts reclassified from AOCI, net	8		—		1,690		1,698
Amortization of unrecognized losses on securities transferred to held to maturity	—		990		—		990
Balance, September 30, 2024	$	(136,952)	$	(22,474)	$	(11,487)	$	(170,913)


	Nine Months Ended September 30, 2025
(dollars in thousands)	Unrealized Gains (Losses) on Debt Securities Available For Sale		Unrecognized Gains (Losses) on Debt Securities Held to Maturity		Unrealized Gains (Losses) on Cash Flow Hedges		Total
Balance, December 31, 2024	$	(165,680)	$	(21,554)	$	(19,805)	$	(207,039)
Unrealized holding gains (losses), net	44,895		—		6,876		51,771

Amounts reclassified from AOCI, net	11,367		—		4,919		16,286
Amortization of unrecognized losses on securities transferred to held to maturity	—		2,181		—		2,181
Balance, September 30, 2025	$	(109,418)	$	(19,373)	$	(8,010)	$	(136,801)


	Nine Months Ended September 30, 2024
(dollars in thousands)	Unrealized Gains (Losses) on Debt Securities Available For Sale		Unrecognized Gains (Losses) on Debt Securities Held to Maturity		Unrealized Gains (Losses) on Cash Flow Hedges		Total
Balance, December 31, 2023	$	(176,636)	$	(25,473)	$	(16,694)	$	(218,803)
Unrealized holding gains (losses), net	34,810		—		211		35,021

Amounts reclassified from AOCI, net	4,874		—		4,996		9,870
Amortization of unrecognized losses on securities transferred to held to maturity	—		2,999		—		2,999
Balance, September 30, 2024	$	(136,952)	$	(22,474)	$	(11,487)	$	(170,913)

Cover Page - shares	9 Months Ended
Cover Page - shares	Sep. 30, 2025	Nov. 06, 2025
Document Information [Line Items]
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Sep. 30, 2025
Document Transition Report	false
Entity File Number	0-15950
Entity Registrant Name	FIRST BUSEY CORPORATION
Entity Incorporation, State or Country Code	NV
Entity Tax Identification Number	37-1078406
Entity Address, Address Line One	11440 Tomahawk Creek Parkway
Entity Address, City or Town	Leawood
Entity Address, State or Province	KS
Entity Address, Postal Zip Code	66211
City Area Code	(217)
Local Phone Number	365-4544
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		88,409,043
Current Fiscal Year End Date	--12-31
Document Fiscal Year Focus	2025
Document Fiscal Period Focus	Q3
Entity Central Index Key	0000314489
Amendment Flag	false
Common Stock, $0.001 par value
Document Information [Line Items]
Title of 12(b) Security	Common Stock, $0.001 par value
Trading Symbol	BUSE
Security Exchange Name	NASDAQ
Depositary Shares, each representing a 1/40th interest in a share of 8.25% Fixed-Rate Series B Non-Cumulative Perpetual Preferred Stock, $0.001 par value
Document Information [Line Items]
Title of 12(b) Security	Depositary Shares, each representing a 1/40th interest in a share of 8.25% Fixed-Rate Series B Non-Cumulative Perpetual Preferred Stock
Trading Symbol	BUSEP
Security Exchange Name	NASDAQ

PORTFOLIO LOANS

9 Months Ended

Sep. 30, 2025

Accounts, Notes, Loans and Financing Receivable, Gross, Allowance, and Net [Abstract]

PORTFOLIO LOANS

NOTE 4. PORTFOLIO LOANS

Loan Categories

Busey’s lending can be summarized in two primary categories: commercial and retail. Loans within these categories are further classified by lending activity: C&I and other commercial, commercial real estate, real estate construction, retail real estate, and retail other. Distributions of the loan portfolio by loan category and lending activity is presented in the following table:


	As of
(dollars in thousands)	September 30, 2025		December 31, 2024
Commercial loans
C&I and other commercial	$	4,395,871	$	1,904,515
CRE	5,424,095		3,269,564
Real estate construction	1,099,524		378,209
Total commercial loans	10,919,490		5,552,288
Retail loans
Retail real estate	2,196,246		1,696,457
Retail other	482,530		448,342
Total retail loans	2,678,776		2,144,799

Total portfolio loans	13,598,266		7,697,087
ACL	(174,181)		(83,404)
Portfolio loans, net	$	13,424,085	$	7,613,683

Net deferred loan origination costs included in the balances above were $8.8 million as of September 30, 2025, compared to $12.5 million as of December 31, 2024. Net accretable purchase accounting adjustments included in the balances above reduced loans by $92.0 million as of September 30, 2025, and $8.8 million as of December 31, 2024.

Other than loans acquired through acquisition activities, Busey did not purchase any retail real estate loans during the three and nine months ended September 30, 2025. Busey did not purchase any retail real estate loans during the three months ended September 30, 2024, and elected to purchase $6.9 million of retail real estate loans during the nine months ended September 30, 2024.

Pledged Loans


	As of
(dollars in thousands)	September 30, 2025		December 31, 2024
Pledged loans
FHLB	$	5,018,506	$	4,813,600
Federal Reserve Bank	1,973,933		765,824
Total pledged loans	$	6,992,439	$	5,579,424

Risk Grading

Busey utilizes a loan grading scale to assign a risk grade to all of its loans. A description of the general characteristics of each grade is as follows:

•Pass – This category includes loans that are all considered acceptable credits, ranging from investment or near investment grade, to loans made to borrowers who exhibit credit fundamentals that meet or exceed industry standards.

•Watch – This category includes loans that warrant a higher-than-average level of monitoring to ensure that weaknesses do not cause the inability of the credit to perform as expected. These loans are not necessarily a problem due to other inherent strengths of the credit, such as guarantor strength, but have above average concern and monitoring.

•Special mention – This category is for “Other Assets Specially Mentioned” loans that have potential weaknesses, which may, if not checked or corrected, weaken the asset or inadequately protect Busey’s credit position at some future date.

•Substandard – This category includes “Substandard” loans, determined in accordance with regulatory guidelines, for which the accrual of interest has not been stopped. Assets so classified must have a well-defined weakness or weaknesses that jeopardize the liquidation of the debt. They are characterized by the distinct possibility that Busey will sustain some loss if the deficiencies are not corrected.

•Substandard non-accrual – This category includes loans that have all the characteristics of a “Substandard” loan with additional factors that make collection in full highly questionable and improbable. Such loans are placed on non-accrual status and may be dependent on collateral with a value that is difficult to determine.

All loans are graded at their inception. Commercial lending relationships that are $2.0 million or less are usually processed through an expedited underwriting process. Most commercial loans greater than $2.0 million are included in a portfolio review at least annually. Commercial loans greater than $0.35 million that have a grading of special mention or worse are typically reviewed on a quarterly basis. Interim reviews may take place if circumstances of the borrower warrant a more frequent review.

The following table is a summary of Busey’s portfolio loans by risk grade, segregated by loan category:


	As of September 30, 2025
(dollars in thousands)	Pass		Watch		Special Mention		Substandard		Substandard Non-accrual		Total
Commercial loans
C&I and other commercial	$	3,707,153	$	433,278	$	152,267	$	74,109	$	29,064	$	4,395,871
CRE	4,453,517		794,313		147,237		21,228		7,800		5,424,095
Real estate construction	1,011,685		56,664		25,653		5,227		295		1,099,524
Total commercial loans	9,172,355		1,284,255		325,157		100,564		37,159		10,919,490
Retail loans
Retail real estate	2,170,254		7,320		7,608		2,759		8,305		2,196,246
Retail other	481,892		—		—		6		632		482,530
Total retail loans	2,652,146		7,320		7,608		2,765		8,937		2,678,776
Total portfolio loans	$	11,824,501	$	1,291,575	$	332,765	$	103,329	$	46,096	$	13,598,266


	As of December 31, 2024
(dollars in thousands)	Pass		Watch		Special Mention		Substandard		Substandard Non-accrual		Total
Commercial loans
C&I and other commercial	$	1,545,338	$	281,424	$	36,152	$	37,749	$	3,852	$	1,904,515
CRE	2,744,018		438,945		55,041		16,507		15,053		3,269,564
Real estate construction	345,908		26,833		221		5,224		23		378,209
Total commercial loans	4,635,264		747,202		91,414		59,480		18,928		5,552,288
Retail loans
Retail real estate	1,680,640		9,408		882		2,543		2,984		1,696,457
Retail other	448,166		—		—		—		176		448,342
Total retail loans	2,128,806		9,408		882		2,543		3,160		2,144,799
Total portfolio loans	$	6,764,070	$	756,610	$	92,296	$	62,023	$	22,088	$	7,697,087

Risk grades of portfolio loans and gross charge-offs are presented in the tables below by lending activity, further sorted by origination year:


	As of and For The Nine Months Ended September 30, 2025
Risk Grade Ratings	Term Loans Amortized Cost Basis by Origination Year												Revolving Loans		Total
(dollars in thousands)	2025		2024		2023		2022		2021		Prior
C&I and other commercial
Pass	$	659,612	$	722,192	$	425,370	$	238,755	$	192,946	$	151,925	$	1,316,353	$	3,707,153
Watch	26,374		79,588		66,467		46,942		55,238		18,233		140,436		433,278
Special Mention	17,388		17,339		25,541		43,362		4,974		2,913		40,750		152,267
Substandard	10,422		1,965		16,543		4,216		10,159		3,771		27,033		74,109
Substandard non-accrual	4,601		2,343		644		1,318		640		5,048		14,470		29,064
Total C&I and other commercial	718,397		823,427		534,565		334,593		263,957		181,890		1,539,042		4,395,871
Gross charge-offs	$	1,246	$	2,626	$	4,347	$	1,440	$	13,591	$	11,254	$	4,550	$	39,054

CRE
Pass	631,171		487,489		703,228		1,216,265		776,293		600,081		38,990		4,453,517
Watch	169,711		56,362		139,202		156,277		186,841		83,665		2,255		794,313
Special Mention	50,239		23,098		5,093		14,139		37,467		16,067		1,134		147,237
Substandard	1,714		708		914		9,046		—		8,628		218		21,228
Substandard non-accrual	82		—		4,548		—		1		3,169		—		7,800
Total CRE	852,917		567,657		852,985		1,395,727		1,000,602		711,610		42,597		5,424,095
Gross charge-offs	1,297		11,057		—		—		253		—		—		12,607

Real estate construction
Pass	240,725		328,610		125,079		215,814		25,158		3,632		72,667		1,011,685
Watch	1,221		43,492		3,588		—		177		—		8,186		56,664
Special Mention	18,233		—		—		—		7,420		—		—		25,653
Substandard	5,165		—		—		—		62		—		—		5,227
Substandard non-accrual	—		274		—		—		21		—		—		295
Total real estate construction	265,344		372,376		128,667		215,814		32,838		3,632		80,853		1,099,524
Gross charge-offs	—		—		—		—		—		—		—		—

Retail real estate
Pass	111,695		138,069		304,874		457,128		379,646		533,444		245,398		2,170,254
Watch	2,696		606		489		1,520		280		1,160		569		7,320
Special Mention	69		84		4,052		1,479		1,705		—		219		7,608
Substandard	1,000		—		111		447		489		712		—		2,759
Substandard non-accrual	212		307		39		319		85		3,205		4,138		8,305
Total retail real estate	115,672		139,066		309,565		460,893		382,205		538,521		250,324		2,196,246
Gross charge-offs	85		—		—		—		—		51		36		172

Retail other
Pass	6,415		6,769		37,741		36,632		6,150		703		387,482		481,892
Watch	—		—		—		—		—		—		—		—
Special Mention	—		—		—		—		—		—		—		—
Substandard	—		—		—		—		—		6		—		6
Substandard non-accrual	35		—		93		99		—		—		405		632
Total retail other	6,450		6,769		37,834		36,731		6,150		709		387,887		482,530
Gross charge-offs	318		147		253		41		—		74		—		833

Total portfolio loans	$	1,958,780	$	1,909,295	$	1,863,616	$	2,443,758	$	1,685,752	$	1,436,362	$	2,300,703	$	13,598,266
Total gross charge-offs	$	2,946	$	13,830	$	4,600	$	1,481	$	13,844	$	11,379	$	4,586	$	52,666


	As of and For The Year Ended December 31, 2024
Risk Grade Ratings	Term Loans Amortized Cost Basis by Origination Year												Revolving Loans		Total
(dollars in thousands)	2024		2023		2022		2021		2020		Prior
C&I and other commercial
Pass	$	320,831	$	147,909	$	163,870	$	125,053	$	74,146	$	117,234	$	596,295	$	1,545,338
Watch	38,734		49,394		44,709		16,393		2,175		20,964		109,055		281,424
Special Mention	1,718		2,293		5,658		2,634		106		2,540		21,203		36,152
Substandard	15,186		6,545		788		591		320		2,424		11,895		37,749
Substandard non-accrual	65		141		464		—		42		852		2,288		3,852
Total C&I and other commercial	376,534		206,282		215,489		144,671		76,789		144,014		740,736		1,904,515
Gross charge-offs	$	—	$	14,980	$	148	$	22	$	—	$	303	$	—	$	15,453

CRE
Pass	291,503		354,591		755,266		645,994		356,867		314,340		25,457		2,744,018
Watch	115,078		132,900		60,611		62,408		28,320		38,733		895		438,945
Special Mention	39,252		643		8,020		1,395		4,165		1,517		49		55,041
Substandard	6,983		355		4,628		50		95		4,346		50		16,507
Substandard non-accrual	15,000		39		—		—		14		—		—		15,053
Total CRE	467,816		488,528		828,525		709,847		389,461		358,936		26,451		3,269,564
Gross charge-offs	—		—		—		2,999		—		315		—		3,314

Real estate construction
Pass	159,825		134,450		12,205		24,781		2,213		1,124		11,310		345,908
Watch	20,170		6,455		—		208		—		—		—		26,833
Special Mention	—		—		—		221		—		—		—		221
Substandard	5,224		—		—		—		—		—		—		5,224
Substandard non-accrual	—		—		—		23		—		—		—		23
Total real estate construction	185,219		140,905		12,205		25,233		2,213		1,124		11,310		378,209
Gross charge-offs	—		—		—		—		—		—		—		—

Retail real estate
Pass	101,582		237,306		366,820		354,380		147,236		267,431		205,885		1,680,640
Watch	1,255		550		2,733		3,377		872		124		497		9,408
Special Mention	151		—		344		—		—		372		15		882
Substandard	—		243		1,018		503		—		776		3		2,543
Substandard non-accrual	—		—		344		91		152		1,526		871		2,984
Total retail real estate	102,988		238,099		371,259		358,351		148,260		270,229		207,271		1,696,457
Gross charge-offs	—		—		—		—		—		168		—		168

Retail other
Pass	4,996		55,665		57,944		12,207		2,304		589		314,461		448,166



Substandard non-accrual	—		94		67		4		—		11		—		176
Total retail other	4,996		55,759		58,011		12,211		2,304		600		314,461		448,342
Gross charge-offs	9		31		106		78		4		403		—		631

Total portfolio loans	$	1,137,553	$	1,129,573	$	1,485,489	$	1,250,313	$	619,027	$	774,903	$	1,300,229	$	7,697,087
Total gross charge-offs	$	9	$	15,011	$	254	$	3,099	$	4	$	1,189	$	—	$	19,566

Past Due and Non-accrual Loans

An analysis of portfolio loans that were past due and still accruing, or on a non-accrual status, is presented in the table below:


	As of September 30, 2025
	Loans past due, still accruing						Non-accrual Loans		Non-accrual Loans with No Allowance for Credit Losses
(dollars in thousands)	30-59 Days		60-89 Days		90+Days
Commercial loans
C&I and other commercial	$	996	$	1,450	$	861	$	29,064	$	6,685
CRE	2,815		6,289		78		7,800		1,543
Real estate construction	—		3,233		347		295		157
Past due and non-accrual commercial loans	3,811		10,972		1,286		37,159		8,385
Retail loans
Retail real estate	2,626		448		102		8,305		348
Retail other	929		128		30		632		—
Past due and non-accrual retail loans	3,555		576		132		8,937		348
Total past due and non-accrual loans	$	7,366	$	11,548	$	1,418	$	46,096	$	8,733


	As of December 31, 2024
	Loans past due, still accruing						Non-accrual Loans		Non-accrual Loans with No Allowance for Credit Losses
(dollars in thousands)	30-59 Days		60-89 Days		90+Days
Commercial loans
C&I and other commercial	$	95	$	—	$	—	$	3,852	$	1,224
CRE	42		2,759		—		15,053		15,000
Real estate construction	41		—		—		23		—
Past due and non-accrual commercial loans	178		2,759		—		18,928		16,224
Retail loans
Retail real estate	3,280		683		1,115		2,984		194
Retail other	1,094		130		34		176		—
Past due and non-accrual retail loans	4,374		813		1,149		3,160		194
Total past due and non-accrual loans	$	4,552	$	3,572	$	1,149	$	22,088	$	16,418

Gross interest income recorded on 90+ days past due loans, and that would have been recorded on non-accrual loans if they had been accruing interest in accordance with their original terms, was $0.9 million and $2.1 million for the three and nine months ended September 30, 2025, respectively, and was $0.1 million and $0.6 million for the three and nine months ended September 30, 2024, respectively. The amount of interest collected on those loans and recognized on a cash basis that was included in interest income was immaterial for the three and nine months ended September 30, 2025 and 2024.

Loan Modifications for Borrowers Experiencing Financial Difficulty


	Three Months Ended September 30, 2025
(dollars in thousands)	Interest Rate Reduction		% of Total Class of Financing Receivable1		Payment Deferral		% of Total Class of Financing Receivable2		Term Extension		% of Total Class of Financing Receivable3
Modified Loans
C&I and other commercial	$	263	—	%	$	2,444	0.1	%	$	10,417	0.2	%
CRE	—		—	%	1,944		—	%	461		—	%



Total of loans modified during the period4	$	263	—	%	$	4,388	—	%	$	10,878	0.1	%

___________________________________________

1.Modified loans represented an insignificant portion of C&I and other commercial loans, and an insignificant portion of total loans, in both cases rounding to zero percent.

2.Modified loans represented an insignificant portion of CRE loans, and an insignificant portion of total loans, in both cases rounding to zero percent.

3.Modified loans represented an insignificant portion of CRE loans, rounding to zero percent.

4.All modifications were for loans classified as substandard.


	Three Months Ended September 30, 2024
(dollars in thousands)	Payment Deferral		% of Total Class of Financing Receivable1		Term Extension2		% of Total Class of Financing Receivable
Modified Loans
C&I and other commercial	$	325	—	%	$	14,537	0.8	%
CRE	—		—	%	18,448		0.5	%
Real estate construction	—		—	%	5,250		1.3	%


Total of loans modified during the period3	$	325	—	%	$	38,235	0.5	%

___________________________________________

1.Modified loans represented an insignificant portion of C&I and other commercial loans, and an insignificant portion of total loans, in both cases rounding to zero percent.

2.Modifications to extend loan terms also included, in some cases, interest rate increases during the extension period.

3.All modifications were for loans classified as substandard.


	Nine Months Ended September 30, 2025
(dollars in thousands)	Interest Rate Reduction		% of Total Class of Financing Receivable1		Payment Deferral		% of Total Class of Financing Receivable2		Term Extension		% of Total Class of Financing Receivable2
Modified Loans
C&I and other commercial	$	263	—	%	$	13,005	0.3	%	$	22,314	0.5	%
CRE	—		—	%	1,944		—	%	823		—	%
Real estate construction	—		—	%	—		—	%	5,165		0.5	%


Total of loans modified during the period3	$	263	—	%	$	14,949	0.1	%	$	28,302	0.2	%

___________________________________________

1.Modified loans represented an insignificant portion of C&I and other commercial loans, and an insignificant portion of total loans, in both cases rounding to zero percent.

2.Modified loans represented an insignificant portion of CRE loans, rounding to zero percent.

3.With the exception of two loans that were transferred to non-accrual status during the nine months ended September 30, 2025, all modifications were for loans classified as substandard.


	Nine Months Ended September 30, 2024
(dollars in thousands)	Payment Deferral1		% of Total Class of Financing Receivable2		Term Extension1		% of Total Class of Financing Receivable
Modified Loans
C&I and other commercial	$	325	—	%	$	28,073	1.5	%
CRE	—		—	%	19,782		0.6	%
Real estate construction	—		—	%	5,250		1.3	%


Total of loans modified during the period3	$	325	—	%	$	53,105	0.7	%

___________________________________________

1.Modifications to extend loan terms also included, in some cases, interest rate increases during the extension period.

2.Modified loans represented an insignificant portion of C&I and other commercial loans, rounding to zero percent.

3.All modifications were for loans classified as substandard.


	Three Months Ended September 30,			Nine Months Ended September 30,
	2025				2024	2025				2024
	Weighted Average Interest Rate Reduction		Weighted Average Term Extension			Weighted Average Term Extension	Weighted Average Interest Rate Reduction		Weighted Average Term Extension		Weighted Average Term Extension
C&I and other commercial	5.00	%	6 months			6 months	5.00	%	10 months		1.2 years
CRE	—	%	8 months			4 months	—	%	1.3 years		4 months
Real estate construction	—	%	—			6 months	—	%	1.3 years		6 months


Aggregate effect	5.00	%	6 months			5 months	5.00	%	11 months		10 months

Payment deferrals for borrowers experiencing financial difficulty can include deferrals of 3 or more payments to the end of the loan, accommodations to restructure the payment terms of the loan, or accommodations to allow for an interest-only period on the loan.

Performance of Modified Loans

Busey closely monitors the performance of the loans that are modified for borrowers experiencing financial difficulty to understand the effectiveness of its modification efforts. The following table depicts the payment performance of loans modified during the last twelve months:


	As of September 30, 2025
(dollars in thousands)	Current		30-89 Days		90+ Days		Non-accrual
Modified Loans
C&I and other commercial	$	32,062	$	—	$	—	$	4,038
CRE	4,147		—		—		—
Real estate construction	5,165		—		—		—


Loans modified during the last twelve months	$	41,374	$	—	$	—	$	4,038

Busey had commitments of $0.4 million as of September 30, 2025, to lend additional funds to debtors experiencing financial difficulty for whom Busey modified a loan within the past twelve months. Busey did not have any commitments as of December 31, 2024, to lend additional funds to debtors experiencing financial difficulty for whom Busey had modified a loan within the past twelve months.


	Three Months Ended September 30,		Nine Months Ended September 30,
	2025			2025
(dollars in thousands)	Term Extension				Payment Deferral		Term Extension
Loans with Subsequent Defaults
C&I and other commercial	$	3,571			$	467	$	3,571




Modified loans with subsequent defaults	$	3,571			$	467	$	3,571

No loans had a default during the three or nine months ended September 30, 2024, after having been modified during the twelve months before that default for borrowers experiencing financial difficulty.

Collateral Dependent Loans

Management's evaluation as to the ultimate collectability of loans includes estimates regarding future cash flows from operations and the value of property, real and personal, pledged as collateral. These estimates are affected by changing economic conditions and the economic prospects of borrowers. Collateral dependent loans are loans in which repayment is expected to be provided solely by the operation or sale of the underlying collateral and there are no other available and reliable sources of repayment. Loans are written down to the lower of cost or fair value of the underlying collateral, less estimated costs to sell. Busey had $39.0 million and $19.3 million of collateral dependent loans secured by real estate or business assets as of September 30, 2025, and December 31, 2024, respectively.

Foreclosures

Busey’s recorded investment in residential real estate loans that were in the process of foreclosure was $6.1 million as of September 30, 2025. Busey follows Federal Housing Finance Agency guidelines on single-family foreclosures and real estate owned evictions on portfolio loans.

Allowance for Credit Losses

The ACL is a valuation account that is deducted from the portfolio loans’ amortized cost bases to present the net amount expected to be collected on the portfolio loans. The ACL is established through the provision for credit losses charged to income. Portfolio loans are charged off against the ACL when management believes the uncollectibility of a loan balance is confirmed. Recoveries are recognized up to the aggregate amount of previously charged-off balances.

Management estimates the ACL balance using relevant available information from internal and external sources relating to past events, current conditions, and reasonable and supportable forecasts. Historical credit loss experience provides the basis for the estimation of expected credit losses. The ACL consists of three components: (i) specific allocations/individual reserves; (ii) quantitative reserves; and (iii) qualitative reserves.

•Specific allocations/individual reserves – When a loan no longer exhibits risk characteristics that are similar to other loans, that loan is individually evaluated. Individual reserves are calculated for loans that are on a non-accrual status that are greater than a defined dollar threshold or loans that have disparate risk characteristics. Reserves may be based on collateral, for collateral-dependent loans, or on quantitative and qualitative factors, including expected cash flow, market sentiment, and guarantor support.

•Quantitative reserves – Busey implemented a new non-discounted cash flow model in the second quarter of 2025 that used combined historical loan data from Busey Bank beginning in 2004 and CrossFirst Bank since its inception in 2007. The model incorporates various baseline forecast scenarios and national unemployment rates with either national gross domestic product, the national home price index, or the national commercial real estate price index. Further, prepayment and curtailment expectations are factored into the model. Due to the continued economic uncertainty in the markets in which the Company operates, Busey will continue to utilize a forecast period of 12 months with an immediate reversion to historical loss rates beyond this forecast period in its ACL estimate.

•Qualitative reserves – Busey uses qualitative factors to adjust the historical loss factors for current and forecasted conditions. Busey considers the ten qualitative factors identified in the Interagency Guidance and ASC Topic 326 at each reporting date.


	Three Months Ended September 30, 2025
(dollars in thousands)	C&I and Other Commercial		CRE		Real Estate Construction		Retail Real Estate		Retail Other		Total
ACL balance, June 30, 2025	$	68,578	$	70,935	$	13,072	$	29,042	$	1,707	$	183,334


Provision for loan losses	(4,768)		1,323		(880)		739		281		(3,305)
Charged-off	(5,753)		(1,438)		—		(53)		(204)		(7,448)
Recoveries	1,379		24		1		115		81		1,600
ACL balance, September 30, 2025	$	59,436	$	70,844	$	12,193	$	29,843	$	1,865	$	174,181


	Three Months Ended September 30, 2024
(dollars in thousands)	C&I and Other Commercial		CRE		Real Estate Construction		Retail Real Estate		Retail Other		Total
ACL balance, June 30, 2024	$	20,286	$	35,104	$	3,722	$	23,729	$	2,385	$	85,226

Provision for loan losses	715		(1,158)		39		120		286		2
Charged-off	(202)		(215)		—		(32)		(225)		(674)
Recoveries	210		4		10		162		41		427
ACL balance, September 30, 2024	$	21,009	$	33,735	$	3,771	$	23,979	$	2,487	$	84,981


	Nine Months Ended September 30, 2025
(dollars in thousands)	C&I and Other Commercial		CRE		Real Estate Construction		Retail Real Estate		Retail Other		Total
ACL balance, December 31, 2024	$	21,589	$	32,301	$	3,345	$	23,711	$	2,458	$	83,404
Day 1 PCD1	75,569		21,588		2,112		1,430		84		100,783
Day 2 Provision for loan losses2	22,648		15,104		2,911		1,628		142		42,433
Provision for loan losses	(23,008)		14,300		3,731		2,833		(137)		(2,281)
Charged-off	(39,054)		(12,607)		—		(172)		(833)		(52,666)
Recoveries	1,692		158		94		413		151		2,508
ACL balance, September 30, 2025	$	59,436	$	70,844	$	12,193	$	29,843	$	1,865	$	174,181

___________________________________________

1.The Day 1 PCD is attributable to the CrossFirst acquisition (see “Note 2. Mergers and Acquisitions”), and represents the initial adjustment to the fair value of the PCD loans.

2.The Day 2 provision for loan losses is attributable to the CrossFirst acquisition (see “Note 2. Mergers and Acquisitions”), and represents the initial provision for non-PCD loans.


	Nine Months Ended September 30, 2024
(dollars in thousands)	C&I and Other Commercial		CRE		Real Estate Construction		Retail Real Estate		Retail Other		Total
ACL balance, December 31, 2023	$	21,256	$	35,465	$	5,163	$	26,298	$	3,558	$	91,740
Day 1 PCD1	824		322		—		96		1		1,243
Provision for loan losses	13,958		(1,882)		(1,449)		(2,624)		(686)		7,317
Charged-off	(15,433)		(315)		—		(159)		(503)		(16,410)
Recoveries	404		145		57		368		117		1,091
ACL balance, September 30, 2024	$	21,009	$	33,735	$	3,771	$	23,979	$	2,487	$	84,981

___________________________________________

1.The Day 1 PCD is attributable to the M&M acquisition (see “Note 2. Mergers and Acquisitions.”)

Net charge-offs during the nine months ended September 30, 2025, included $35.5 million related to PCD loans acquired from CrossFirst Bank, which were fully reserved at acquisition and did not require recording additional provision expense.

ACCUMULATED OTHER COMPREHENSIVE INCOME (LOSS) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2025	Sep. 30, 2024	Sep. 30, 2025	Sep. 30, 2024
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	$ 2,412,546	$ 1,333,810	$ 1,383,269	$ 1,271,981
Ending balance	2,448,835	1,402,884	2,448,835	1,402,884
Total
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	(155,311)	(220,326)	(207,039)	(218,803)
Ending balance	(136,801)	(170,913)	(136,801)	(170,913)
Unrealized Gains (Losses) on Debt Securities Available For Sale and Unrealized Gains (Losses) on Cash Flow Hedges
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Unrealized holding gains (losses), net	15,963	46,725	51,771	35,021
Amounts reclassified from AOCI, net and amortization of unrecognized losses on securities transferred to held to maturity	1,722	1,698	16,286	9,870
Unrealized Gains (Losses) on Debt Securities Available For Sale
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	(125,745)	(176,246)	(165,680)	(176,636)
Unrealized holding gains (losses), net	16,326	39,286	44,895	34,810
Amounts reclassified from AOCI, net and amortization of unrecognized losses on securities transferred to held to maturity	1	8	11,367	4,874
Ending balance	(109,418)	(136,952)	(109,418)	(136,952)
Unrealized Gains (Losses) on Cash Flow Hedges
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	(9,368)	(20,616)	(19,805)	(16,694)
Unrealized holding gains (losses), net	(363)	7,439	6,876	211
Amounts reclassified from AOCI, net and amortization of unrecognized losses on securities transferred to held to maturity	1,721	1,690	4,919	4,996
Ending balance	(8,010)	(11,487)	(8,010)	(11,487)
Unrecognized Gains (Losses) on Debt Securities Held to Maturity
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	(20,198)	(23,464)	(21,554)	(25,473)
Amounts reclassified from AOCI, net and amortization of unrecognized losses on securities transferred to held to maturity	825	990	2,181	2,999
Ending balance	$ (19,373)	$ (22,474)	$ (19,373)	$ (22,474)

- Definition

Amount of equity (deficit) attributable to parent. Excludes temporary equity and equity attributable to noncontrolling interest.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 235
-SubTopic 10
-Name Accounting Standards Codification
-Section S50
-Paragraph 1
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Reference 12: http://www.xbrl.org/2003/role/disclosureRef
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Reference 13: http://www.xbrl.org/2003/role/disclosureRef
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+ Details

LEASES - Schedule of Future Undiscounted Lease Payments (Details) - USD ($) $ in Thousands	Sep. 30, 2025	Dec. 31, 2024
Operating Leases
Remainder of 2025	$ 1,618
2026	6,107
2027	5,623
2028	5,107
2029	4,110
2030	3,227
Thereafter	11,121
Total undiscounted cash flows	36,913
Less: Amounts representing interest	5,321
Present value of net future minimum lease payments	31,592	$ 11,040
Finance Leases
Remainder of 2025	123
2026	490
2027	527
2028	540
2029	540
2030	540
Thereafter	6,625
Total undiscounted cash flows	9,385
Less: Amounts representing interest	3,119
Present value of net future minimum lease payments	$ 6,266	$ 0

DERIVATIVE FINANCIAL INSTRUMENTS - Schedule of Interest Rate Swaps Recorded in Noninterest Expense (Details) - Interest Rate Swap - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2025	Sep. 30, 2024	Sep. 30, 2025	Sep. 30, 2024
Derivative [Line Items]
Net change in fair value of interest rate swaps	$ 0	$ 0	$ 0	$ 0
Noninterest expense
Derivative [Line Items]
Gain, receive-fixed, pay-floating	(1,083)	(9,224)	(21)	(3,050)
Loss, receive-floating, pay-fixed	$ 1,083	$ 9,224	$ 21	$ 3,050

OPERATING SEGMENTS AND RELATED INFORMATION - Narrative (Details)	1 Months Ended	9 Months Ended
	Mar. 31, 2025 bankingCenter	Sep. 30, 2025 segment
Segment Reporting [Abstract]
Number of reportable segments		3
Number of operating segments		3
Number of full-service locations \| bankingCenter	79

DERIVATIVE FINANCIAL INSTRUMENTS - Narrative (Details) - USD ($) $ in Thousands	Sep. 30, 2025	Dec. 31, 2024
Interest Rate Swap \| Not Designated as Hedging Instrument
Derivative [Line Items]
Variable rate, commercial loans that are supported by the interest rate swap contracts	$ 1,010,000	$ 719,200
Interest Rate Swap \| Cash Flow Hedging \| Designated as Hedging Instrument
Derivative [Line Items]
Notional amount	500,000	500,000
Prime Loan Swap \| Designated as Hedging Instrument
Derivative [Line Items]
Notional amount	300,000
Prime Loan Swap \| Cash Flow Hedging
Derivative [Line Items]
Notional amount	300,000	300,000
SOFR Loan Swap \| Designated as Hedging Instrument
Derivative [Line Items]
Notional amount	200,000
SOFR Loan Swap \| Cash Flow Hedging
Derivative [Line Items]
Notional amount	$ 200,000	$ 200,000

SIGNIFICANT ACCOUNTING POLICIES (Tables)

9 Months Ended

Sep. 30, 2025

Accounting Policies [Abstract]

Schedule of Stock Issuances

The following tables summarize Busey’s preferred stock issuances:


	September 30, 2025
Title of Eash Issue	Shares Authorized	Shares Issued	Shares Outstanding	Balance		Per Share Preference in Liquidation		Aggregate Liquidation Preference ($ in 000's)

Preferred stock, $0.001 par value:	1,000,000
Series A Non-Cumulative Perpetual Preferred Stock	7,750	7,750	7,750	$	7.75	$	1,000.00	$	7,750
8.25% Fixed-Rate Series B Non-Cumulative Perpetual Preferred Stock	230,000	215,000	215,000	$	215.00	$	1,000.00	$	215,000

Changes in preferred stock issued are presented in the following table:


	Three Months Ended September 30,				Nine Months Ended September 30,
Title of Eash Issue	2025		2024		2025		2024


Series A Non-Cumulative Perpetual Preferred Stock	$	—	$	—	$	7.75	$	—
8.25% Fixed-Rate Series B Non-Cumulative Perpetual Preferred Stock	—		—		215.00		—

- Definition

Tabular disclosure of an entity's stock, including par or stated value per share, number and dollar amount of share subscriptions, shares authorized, shares issued, shares outstanding, number and dollar amount of shares held in an employee trust, dividend per share, total dividends, share conversion features, par value plus additional paid in capital, the value of treasury stock and other information necessary to a fair presentation, and EPS information. Stock by class includes common, convertible, and preferred stocks which are not redeemable or redeemable solely at the option of the issuer. Includes preferred stock with redemption features that are solely within the control of the issuer and mandatorily redeemable stock if redemption is required to occur only upon liquidation or termination of the reporting entity. If more than one issue is outstanding, state the title of each issue and the corresponding dollar amount; dollar amount of any shares subscribed but unissued and the deduction of subscriptions receivable there from; number of shares authorized, issued, and outstanding.

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+ Details

BORROWINGS - Schedule of Long-term Borrowings (Details) $ in Thousands	9 Months Ended
	Sep. 30, 2025 USD ($) note	Dec. 31, 2024 USD ($)
Debt Instrument [Line Items]
Finance lease liabilities	$ 6,266	$ 0
Total long-term borrowings	$ 92,431	$ 0
Weighted average rate for securities sold under agreements to repurchase	2.50%	2.63%
FHLB borrowings
Debt Instrument [Line Items]
Total long-term borrowings	$ 79,174	$ 0
Number of notes \| note	12
Weighted average rate for securities sold under agreements to repurchase	2.22%
Debt, weighted average maturity period	2 years 3 months 18 days
Secured borrowings
Debt Instrument [Line Items]
Total long-term borrowings	$ 6,991	$ 0
Number of notes \| note	9
Debt, weighted average maturity period	17 years 5 months 26 days

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

+ Details

STOCK-BASED COMPENSATION - Employee Stock Purchase Plan and Stock-based Compensation Expense (Details) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2025	Sep. 30, 2024	Sep. 30, 2025	Sep. 30, 2024	Jul. 01, 2021
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Stock option compensation expense	$ 4,298,000	$ 2,291,000	$ 13,125,000	$ 5,828,000
Options
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Stock option compensation expense	0	$ 0	0	$ 0
Unrecognized stock option compensation expense	$ 0		$ 0
Employee Stock Purchase Plan
Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items]
Remaining shares available for issuance (in shares)	314,203		314,203		600,000

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

+ Details

DEPOSITS

9 Months Ended

Sep. 30, 2025

Deposits [Abstract]

DEPOSITS

NOTE 6. DEPOSITS

The composition of Busey’s deposits is presented in the table below:


	As of
(dollars in thousands)	September 30, 2025		December 31, 2024
Deposits
Noninterest-bearing demand deposits	$	3,554,936	$	2,719,907
Interest-bearing transaction deposits	3,171,255		2,423,237
Saving deposits and money market deposits	5,910,183		3,348,711
Time deposits	2,433,788		1,490,635
Total deposits	$	15,070,162	$	9,982,490

Additional information about Busey’s deposits is presented in the table below:


	As of
(dollars in thousands)	September 30, 2025		December 31, 2024
Brokered interest-bearing transaction deposits	$	50,240	$	—
Brokered savings deposits and money market deposits	10,000		6,002
Brokered time deposits	65,192		7,088
Aggregate amount of time deposits with a minimum denomination of $100,000	1,621,232		860,193
Aggregate amount of time deposits with a minimum denomination that meets or exceeds the FDIC insurance limit of $250,000	807,378		334,503

Scheduled maturities of time deposits are presented in the table below:


(dollars in thousands)	As of September 30, 2025
Time deposits by schedule of maturities
Remainder of 2025	$	860,688
2026	1,531,369
2027	23,194
2028	10,487
2029	5,218
2030	2,409
Thereafter	423
Time deposits	$	2,433,788