SIGNIFICANT ACCOUNTING POLICIES (Policies)	6 Months Ended
Jun. 30, 2026
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. First Busey’s stock is traded on The Nasdaq Global Select Market, with its common stock trading under the symbol “BUSE” and its depositary shares of Busey Series B Preferred Stock trading under the symbol “BUSEP.” Busey operates and reports its business in three segments: Banking, Wealth Management, and FirsTech. Busey provides a full range of banking and wealth management services through Busey Bank, and payment technology solutions through Busey Bank’s wholly owned subsidiary, FirsTech. For additional information about Busey's operating segments, see “Note 16. Operating Segments and Related Information.” 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 2025 Annual Report. These interim unaudited consolidated financial statements serve to update Busey's 2025 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 consolidated financial statements and the disclosures provided. Actual results could differ from those estimates. Critical accounting estimates which are particularly susceptible to significant change relate to the fair value of assets acquired and liabilities assumed in business combinations, goodwill, income taxes, and the determination of the ACL.
Trust Assets	Trust Assets Assets held for customers in a fiduciary or agency capacity, other than trust cash on deposit at Busey Bank, are not Busey’s assets and, accordingly, are not included in the accompanying unaudited consolidated financial statements.
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 with original maturities of three months or less. The carrying amount of these instruments is considered a reasonable estimate of fair value.
Interest- Bearing Time Deposits in Other Banks	Interest-bearing time deposits in other banks Interest-bearing time deposits in other banks consist of certificates of deposit with original maturities greater than three months and are carried at amortized cost.
Income Taxes	Income Taxes Busey is subject to income taxes in U.S. federal and various state jurisdictions. First Busey 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. Busey monitors evolving federal and state tax legislation and its potential impact on operations on an ongoing basis. As of June 30, 2026, Busey remains 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 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 to reduce complexity in estimating the ACL for current accounts receivable and current contract assets arising from transactions subject to ASC 606 by permitting an entity to assume that current conditions as of the balance sheet date will remain static for the remaining life of these assets. Busey adopted this ASU prospectively for annual and interim reporting periods beginning January 1, 2026, and elected the practical expedient for in-scope assets. Loans and other financial assets measured at amortized cost are not within the scope of this ASU. Because Busey does not currently have in-scope assets, adoption of this standard did not have a material impact on Busey’s financial position or 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. This ASU was adopted on a prospective basis for annual and interim reporting periods beginning January 1, 2026. Because Busey does not currently have any convertible debt, adoption of this standard did not have a material impact on Busey’s financial position or results of operations. Recently Issued Accounting Standards Not Yet Adopted In May 2026, the FASB issued ASU 2026‑02 “Environmental Credits and Environmental Credit Obligations (Topic 818),” which establishes recognition, measurement, presentation, and disclosure requirements for environmental credits and environmental credit obligations. This update is to be applied on a retrospective basis, and will be effective for Busey for annual and interim reporting periods beginning January 1, 2028. Early adoption is permitted as of the beginning of an annual reporting period. Busey is currently evaluating the applicability and effect of this ASU on its financial position, results of operations, and related disclosures. In November 2025, the FASB issued ASU 2025-09 “Derivatives and Hedging (Topic 815): Hedge Accounting Improvements” to expand the hedged risks permitted to be aggregated in a group of individual forecasted transactions, enabling entities to apply hedge accounting treatment to a broader portfolio of forecasted transactions. Under the amendments in this update, a group of individual forecasted transactions can be designated as a cash flow hedge if they have a similar risk exposure. Individual forecasted transactions are considered to have a similar risk exposure when the derivative used as the hedging instrument is highly effective against each hedged risk in the group. This update is to be applied on a prospective basis for all hedging relationships; there is an option to elect to adopt the amendments in this update for hedging relationships that exist as of the date of adoption. This update 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 November 2025, the FASB issued ASU 2025-08 “Financial Instruments—Credit Losses (Topic 326): Purchased Loans” to expand the population of purchased loans subject to a “gross-up” accounting treatment, under which an ACL is recognized for the estimated credit losses at the acquisition date and the loan values are recorded at their estimated fair values plus a gross-up to offset the ACL. The gross-up accounting treatment prevents double recognition of an ACL through credit loss expense that was already considered in the fair value measurement of acquired loans. Under the guidance in this update, the gross-up accounting treatment applies to all non-PCD loans (excluding credit cards) acquired in a business combination and all non-PCD loans (excluding credit cards) that were purchased at least 90 days after origination and for which the purchaser was not involved in the loan origination. This update is to be applied prospectively, and will be effective for Busey for annual and interim reporting periods beginning January 1, 2027. Early adoption is permitted. For future transactions, Busey will evaluate the effect this ASU may have on its financial position and results of operations. 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 completed 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 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 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 those of the SEC in order to better facilitate comparisons between SEC registrants and entities that are not subject to SEC reporting requirements. The amendments in this ASU should be applied prospectively, and the effective date 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 by June 30, 2027, the pending content of this update will be removed from the ASC and have no further effect. Because this update relates only to disclosure, 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, and noted the following: •On July 13, 2026, Busey entered into a letter agreement with its Chief Executive Officer, which included an equity grant with a three‑year vesting term. First Busey filed a copy of the letter agreement as Exhibit 10.1 to a Current Report filed with the SEC on July 14, 2026. •On July 31, 2026, First Busey filed a C urrent Report with the SEC, announcing the retirement of a member of its board of directors from his position, effective July 29, 2026. Effective at that time, the board of directors passed a resolution to reduce its size to 11 directors. Other than these, there were no significant events subsequent to the quarter ended June 30, 2026, through the filing date of these unaudited consolidated financial statements.
Fair Value Measurements	Allowance for Credit Losses A description of Busey's accounting policies and methodology related to the ACL, including the three components of the ACL—specific allocations/individual reserves, quantitative reserves, and qualitative reserves— is included under the heading “Allowance for Credit Losses” in “Note 1. Significant Accounting Policies” and “Note 4. Portfolio Loan s” in Busey's 2025 Annual Report. There were no significant changes to the methodology during the six months ended June 30, 2026. Busey's quantitative 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. Due to the continued economic uncertainty in the markets in which Busey operates, in estimating the ACL, Busey uses a forecast period of 12 months with an immediate reversion to historical loss rates beyond this forecast period. 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 Busey 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 Busey’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. 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).

SIGNIFICANT ACCOUNTING POLICIES (Policies)

6 Months Ended

Jun. 30, 2026

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

Busey operates and reports its business in three segments: Banking, Wealth Management, and FirsTech. Busey provides a full range of banking and wealth management services through Busey Bank, and payment technology solutions through Busey Bank’s wholly owned subsidiary, FirsTech. For additional information about Busey's operating segments, see “Note 16. Operating Segments and Related Information.” 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 2025 Annual Report. These interim unaudited consolidated financial statements serve to update Busey's 2025 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 consolidated financial statements and the disclosures provided. Actual results could differ from those estimates. Critical accounting estimates which are particularly susceptible to significant change relate to the fair value of assets acquired and liabilities assumed in business combinations, goodwill, income taxes, and the determination of the ACL.

Trust Assets

Assets held for customers in a fiduciary or agency capacity, other than trust cash on deposit at Busey Bank, are not Busey’s assets and, accordingly, are not included in the accompanying unaudited consolidated financial statements.

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 with original maturities of three months or less. The carrying amount of these instruments is considered a reasonable estimate of fair value.

Interest- Bearing Time Deposits in Other Banks

Interest-bearing time deposits in other banks

Interest-bearing time deposits in other banks consist of certificates of deposit with original maturities greater than three months and are carried at amortized cost.

Income Taxes

Busey is subject to income taxes in U.S. federal and various state jurisdictions. First Busey 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. Busey monitors evolving federal and state tax legislation and its potential impact on operations on an ongoing basis.

As of June 30, 2026, Busey remains 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 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 to reduce complexity in estimating the ACL for current accounts receivable and current contract assets arising from transactions subject to ASC 606 by permitting an entity to assume that current conditions as of the balance sheet date will remain static for the remaining life of these assets. Busey adopted this ASU prospectively for annual and interim reporting periods beginning January 1, 2026, and elected the practical expedient for in-scope assets. Loans and other financial assets measured at amortized cost are not within the scope of this ASU. Because Busey does not currently have in-scope assets, adoption of this standard did not have a material impact on Busey’s financial position or 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. This ASU was adopted on a prospective basis for annual and interim reporting periods beginning January 1, 2026. Because Busey does not currently have any convertible debt, adoption of this standard did not have a material impact on Busey’s financial position or results of operations.

Recently Issued Accounting Standards Not Yet Adopted

In May 2026, the FASB issued ASU 2026‑02 “Environmental Credits and Environmental Credit Obligations (Topic 818),” which establishes recognition, measurement, presentation, and disclosure requirements for environmental credits and environmental credit obligations. This update is to be applied on a retrospective basis, and will be effective for Busey for annual and interim reporting periods beginning January 1, 2028. Early adoption is permitted as of the beginning of an annual reporting period. Busey is currently evaluating the applicability and effect of this ASU on its financial position, results of operations, and related disclosures.

In November 2025, the FASB issued ASU 2025-09 “Derivatives and Hedging (Topic 815): Hedge Accounting Improvements” to expand the hedged risks permitted to be aggregated in a group of individual forecasted transactions, enabling entities to apply hedge accounting treatment to a broader portfolio of forecasted transactions. Under the amendments in this update, a group of individual forecasted transactions can be designated as a cash flow hedge if they have a similar risk exposure. Individual forecasted transactions are considered to have a similar risk exposure when the derivative used as the hedging instrument is highly effective against each hedged risk in the group. This update is to be applied on a prospective basis for all hedging relationships; there is an option to elect to adopt the amendments in this update for hedging relationships that exist as of the date of adoption. This update 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 November 2025, the FASB issued ASU 2025-08 “Financial Instruments—Credit Losses (Topic 326): Purchased Loans” to expand the population of purchased loans subject to a “gross-up” accounting treatment, under which an ACL is recognized for the estimated credit losses at the acquisition date and the loan values are recorded at their estimated fair values plus a gross-up to offset the ACL. The gross-up accounting treatment prevents double recognition of an ACL through credit loss expense that was already considered in the fair value measurement of acquired loans. Under the guidance in this update, the gross-up accounting treatment applies to all non-PCD loans (excluding credit cards) acquired in a business combination and all non-PCD loans (excluding credit cards) that were purchased at least 90 days after origination and for which the purchaser was not involved in the loan origination. This update is to be applied prospectively, and will be effective for Busey for annual and interim reporting periods beginning January 1, 2027. Early adoption is permitted. For future transactions, Busey will evaluate the effect this ASU may have on its financial position and results of operations.

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 completed 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 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 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 those of the SEC in order to better facilitate comparisons between SEC registrants and entities that are not subject to SEC reporting requirements. The amendments in this ASU should be applied prospectively, and the effective date 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 by June 30, 2027, the pending content of this update will be removed from the ASC and have no further effect. Because this update relates only to disclosure, 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, and noted the following:

•On July 13, 2026, Busey entered into a letter agreement with its Chief Executive Officer, which included an equity grant with a three‑year vesting term. First Busey filed a copy of the letter agreement as Exhibit 10.1 to a Current Report filed with the SEC on July 14, 2026.

•On July 31, 2026, First Busey filed a C urrent Report with the SEC, announcing the retirement of a member of its board of directors from his position, effective July 29, 2026. Effective at that time, the board of directors passed a resolution to reduce its size to 11 directors.

Other than these, there were no significant events subsequent to the quarter ended June 30, 2026, through the filing date of these unaudited consolidated financial statements.

Fair Value Measurements

Allowance for Credit Losses

A description of Busey's accounting policies and methodology related to the ACL, including the three components of the ACL—specific allocations/individual reserves, quantitative reserves, and qualitative reserves— is included under the heading “Allowance for Credit Losses” in “Note 1. Significant Accounting Policies” and “Note 4. Portfolio Loan s” in Busey's 2025 Annual Report. There were no significant changes to the methodology during the six months ended June 30, 2026.

Busey's quantitative 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. Due to the continued economic uncertainty in the markets in which Busey operates, in estimating the ACL, Busey uses a forecast period of 12 months with an immediate reversion to historical loss rates beyond this forecast period.

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 Busey 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 Busey’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.

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).