Basis of Presentation and Changes in Significant Accounting Policies	9 Months Ended
Sep. 30, 2025
Basis of Presentation and Changes in Significant Accounting Policies
Basis of Presentation and Changes in Significant Accounting Policies	Note 1 – Basis of Presentation and Changes in Significant Accounting Policies The accounting policies followed in the preparation of the interim consolidated financial statements are consistent with those used in the preparation of the annual financial information. The interim consolidated financial statements reflect all normal and recurring adjustments that are necessary, in the opinion of management, for a fair statement of results for the interim period presented. Results for the period ended September 30, 2025, are not necessarily indicative of the results that may be expected for the year ending December 31, 2025. These interim consolidated financial statements and accompanying notes are unaudited and should be read in conjunction with the audited financial statements and notes included in Old Second Bancorp, Inc.’s (the “Company”) annual report on Form 10-K for the year ended December 31, 2024. Unless otherwise indicated, dollar amounts in the tables contained in the notes to the consolidated financial statements are in thousands. Certain items in prior periods have been reclassified to conform to the current presentation. The Company’s consolidated financial statements are prepared in accordance with United States generally accepted accounting principles (“GAAP”) and follow general practices within the banking industry. Application of these principles requires management to make estimates, assumptions, and judgments that affect the amounts reported in the consolidated financial statements and accompanying notes. These estimates, assumptions, and judgments are based on information available as of the date of the consolidated financial statements. Future changes in information may affect these estimates, assumptions, and judgments, which, in turn, may affect amounts reported in the consolidated financial statements. Refer to Changes in Significant Accounting Policies within this Form 10-Q for a description of policies impacted by the acquisition of Bancorp Financial. Recent Accounting Pronouncements The following is a summary of recent accounting pronouncements that have impacted or could potentially affect the Company: ASU 2023-06 – On October 9, 2023, the FASB issued ASU 2023-06 “Disclosure Improvements: Codification Amendments in Response to the SEC’s Disclosure Update and Simplification Initiative.” The amendments in the ASU modify the disclosure or presentation requirements of a variety of topics in the codification. Certain of the amendments represent clarifications to, or technical corrections of, the current requirements. Each amendment in the ASU will only become effective if the SEC removes the related disclosure or presentation requirement from its existing regulations by June 30, 2027. The amendments in this ASU are not expected to have a material impact on the financial statements of the Company. ASU 2023-09 – On December 14, 2023, the FASB issued ASU 2023-09 “Income Taxes (Topic 740): Improvements to Income Tax Disclosures”. The amendments require that public business entities on an annual basis (1) disclose specific categories in the rate reconciliation, and (2) provide additional information for reconciling items that meet a quantitative threshold (if the effect of those reconciling items is equal to or greater than 5 percent of the amount computed by multiplying pretax income (or loss) by the applicable statutory income tax rate). The amendments require that all entities disclose on an annual basis the following information about income taxes paid: (1) The amount of income taxes paid (net of refunds received) disaggregated by federal (national), state, and foreign taxes, and (2) The amount of income taxes paid (net of refunds received) disaggregated by individual jurisdictions in which income taxes paid (net of refunds received) is equal to or greater than 5 percent of total income taxes paid (net of refunds received). The amendments also require that all entities disclose the following information: (1) Income (or loss) from continuing operations before income tax expense (or benefit) disaggregated between domestic and foreign, and (2) Income tax expense (or benefit) from continuing operations disaggregated by federal (national), state, and foreign. The ASU is effective for public business entities for annual periods beginning after December 15, 2024. Early adoption is permitted for annual financial statements that have not yet been issued or made available for issuance. The amendments should be applied on a prospective basis. Retrospective application is permitted. The Company is required to adopt the expanded disclosure requirements of this ASU in its annual financial statements as of December 31, 2025, and does not expect the amendments to have a material impact to the financial statements of the Company. ASU 2024-03 and ASU 2025-01 – On November 4, 2024, the FASB issued ASU 2024-03 “Income Statement—Reporting Comprehensive Income—Expense Disaggregation Disclosures (Subtopic 220-40): Disaggregation of Income Statement Expenses.” This ASU requires public companies to disclose, in the notes to financial statements, specified information about certain costs and expenses at each interim and annual reporting period. Specifically, they will be required to: (1) Disclose the amounts of (a) purchases of inventory; (b) employee compensation; (c) depreciation; (d) intangible asset amortization; and (e) depreciation, depletion, and amortization recognized as part of oil- and gas-producing activities (or other amounts of depletion expense) included in each relevant expense caption; (2) Include certain amounts that are already required to be disclosed under current generally accepted accounting principles (GAAP) in the same disclosure as the other disaggregation requirements; (3) Disclose a qualitative description of the amounts remaining in relevant expense captions that are not separately disaggregated quantitatively; and (4) Disclose the total amount of selling expenses and, in annual reporting periods, an entity’s definition of selling expenses. ASU 2024-03 is effective for public business entities for annual reporting periods beginning after December 15, 2026, and interim reporting periods within annual reporting periods beginning after December 15, 2027, which dates were clarified in ASU 2025-01, and is not expected to have a material impact on the financial statements of the Company. ASU 2025-03 – On May 12, 2025, the FASB issued ASU 2024-03 “Business Combinations (Topic 805) and Consolidation (Topic 810): Determining the Accounting Acquirer in the Acquisition of a Variable Interest Entity.” This ASU revises current guidance for determining the accounting acquirer for a transaction effected primarily by exchanging equity interests in which the legal acquiree is a variable interest entity that meets the definition of a business. The amendments require an entity to consider the same factors that are currently required for determining which entity is the accounting acquirer in other acquisition transactions. This ASU is effective for annual reporting periods beginning after December 15, 2026, and interim reporting periods within those annual reporting periods. Early adoption is permitted in an interim or annual reporting period in which financial statements have not yet been issued (or made available for issuance). If an entity adopts ASU No. 2025-03 in an interim reporting period, it should adopt it as of the beginning of that interim reporting period or the beginning of the annual reporting period that includes that interim reporting period. An entity should apply ASU 2025-03 on a prospective basis to all business combinations that have an acquisition date that occurs on or after the date of initial application of ASU 2025-03. ASU 2025-03 is not expected to have a material impact on the financial statements of the Company. Changes in Significant Accounting Policies Significant accounting policies are presented in Note 1 to the consolidated financial statements included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2024. These policies, along with the disclosures presented in the other financial statement notes and, in this discussion, provide information on how significant assets and liabilities are valued in the consolidated financial statements and how those values are determined. As of July 1, 2025, and as a result of the acquisition of Bancorp Financial, the Company amended its past due and nonaccrual loan policy disclosed in Note 1 of the December 31, 2024, Form 10-K to include a description of the retail non-real estate lending policy. The policy is amended as retail loans secured by collateral other than real estate that become past due 120 cumulative days from the contractual due date should generally be classified as a loss and charged off. In lieu of charging off the entire loan balance, loans with non-real estate collateral may be written down to the value of the collateral, less cost to sell, if repossession of collateral has occurred and collateral is in the Bank’s possession. Retail non-real estate loans covered by this policy include those disclosed within the other and powersport portfolios. There are a variety of modification programs for the powersport portfolio (Holiday, Disaster, Military), of which most are defined within the contractual agreement. Exceptions are made outside of these programs in instances where there is a hardship. The Bank has elected to report the following as modifications to borrowers in financial difficulty: 1) modifications to borrowers who have filed bankruptcy, and 2) modifications for more than three months or more than four times in the last 12 months. As a result of the acquisition, the Company also amended the policy for allowance for credit losses to incorporate the utilization of the vintage methodology on the powersport portfolio. Subsequent Events Dividends On October 21, 2025, our Board of Directors declared a cash dividend of $0.07 per share of common stock payable on November 10, 2025, to stockholders of record as of October 31, 2025; dividends of $3.7 million will be paid to stockholders on November 10, 2025.

Basis of Presentation and Changes in Significant Accounting Policies

9 Months Ended

Sep. 30, 2025

Basis of Presentation and Changes in Significant Accounting Policies

Basis of Presentation and Changes in Significant Accounting Policies

Note 1 – Basis of Presentation and Changes in Significant Accounting Policies

The accounting policies followed in the preparation of the interim consolidated financial statements are consistent with those used in the preparation of the annual financial information. The interim consolidated financial statements reflect all normal and recurring adjustments that are necessary, in the opinion of management, for a fair statement of results for the interim period presented. Results for the period ended September 30, 2025, are not necessarily indicative of the results that may be expected for the year ending December 31, 2025. These interim consolidated financial statements and accompanying notes are unaudited and should be read in conjunction with the audited financial statements and notes included in Old Second Bancorp, Inc.’s (the “Company”) annual report on Form 10-K for the year ended December 31, 2024. Unless otherwise indicated, dollar amounts in the tables contained in the notes to the consolidated financial statements are in thousands. Certain items in prior periods have been reclassified to conform to the current presentation.

The Company’s consolidated financial statements are prepared in accordance with United States generally accepted accounting principles (“GAAP”) and follow general practices within the banking industry. Application of these principles requires management to make estimates, assumptions, and judgments that affect the amounts reported in the consolidated financial statements and accompanying notes. These estimates, assumptions, and judgments are based on information available as of the date of the consolidated financial statements. Future changes in information may affect these estimates, assumptions, and judgments, which, in turn, may affect amounts reported in the consolidated financial statements. Refer to Changes in Significant Accounting Policies within this Form 10-Q for a description of policies impacted by the acquisition of Bancorp Financial.

Recent Accounting Pronouncements

The following is a summary of recent accounting pronouncements that have impacted or could potentially affect the Company:

ASU 2023-06 – On October 9, 2023, the FASB issued ASU 2023-06 “Disclosure Improvements: Codification Amendments in Response to the SEC’s Disclosure Update and Simplification Initiative.” The amendments in the ASU modify the disclosure or presentation requirements of a variety of topics in the codification. Certain of the amendments represent clarifications to, or technical corrections of, the current requirements. Each amendment in the ASU will only become effective if the SEC removes the related disclosure or presentation requirement from its existing regulations by June 30, 2027. The amendments in this ASU are not expected to have a material impact on the financial statements of the Company.

ASU 2023-09 – On December 14, 2023, the FASB issued ASU 2023-09 “Income Taxes (Topic 740): Improvements to Income Tax Disclosures”. The amendments require that public business entities on an annual basis (1) disclose specific categories in the rate reconciliation, and (2) provide additional information for reconciling items that meet a quantitative threshold (if the effect of those reconciling items is equal to or greater than 5 percent of the amount computed by multiplying pretax income (or loss) by the applicable statutory income tax rate). The amendments require that all entities disclose on an annual basis the following information about income taxes paid: (1) The amount of income taxes paid (net of refunds received) disaggregated by federal (national), state, and foreign taxes, and (2) The amount of income taxes paid (net of refunds received) disaggregated by individual jurisdictions in which income taxes paid (net of refunds received) is equal to or greater than 5 percent of total income taxes paid (net of refunds received). The amendments also require that all entities disclose the following information: (1) Income (or loss) from continuing operations before income tax expense (or benefit) disaggregated between domestic and foreign, and (2) Income tax expense (or benefit) from continuing operations disaggregated by federal (national), state, and foreign. The ASU is effective for public business entities for annual periods beginning after December 15, 2024. Early adoption is permitted for annual financial statements that have not yet been issued or made available for issuance. The amendments should be applied on a prospective basis. Retrospective application is permitted. The Company is required to adopt the expanded disclosure requirements of this ASU in its annual financial statements as of December 31, 2025, and does not expect the amendments to have a material impact to the financial statements of the Company.

ASU 2024-03 and ASU 2025-01 – On November 4, 2024, the FASB issued ASU 2024-03 “Income Statement—Reporting Comprehensive Income—Expense Disaggregation Disclosures (Subtopic 220-40): Disaggregation of Income Statement Expenses.” This ASU requires public companies to disclose, in the notes to financial statements, specified information about certain costs and expenses at each interim and annual reporting period. Specifically, they will be required to: (1) Disclose the amounts of (a) purchases of inventory; (b) employee compensation; (c) depreciation; (d) intangible asset amortization; and (e) depreciation, depletion, and amortization recognized as part of oil- and gas-producing activities (or other amounts of depletion expense) included in each relevant expense caption; (2) Include certain amounts that are already required to be disclosed under current generally accepted accounting principles (GAAP) in the same disclosure as the other disaggregation requirements; (3) Disclose a qualitative description of the amounts remaining in relevant expense captions that are not separately disaggregated quantitatively; and (4) Disclose the total amount of selling expenses and, in annual reporting periods, an entity’s definition of selling expenses. ASU 2024-03 is effective for public business entities for annual reporting periods beginning after December 15, 2026, and interim reporting periods within annual reporting periods beginning after December 15, 2027, which dates were clarified in ASU 2025-01, and is not expected to have a material impact on the financial statements of the Company.

ASU 2025-03 – On May 12, 2025, the FASB issued ASU 2024-03 “Business Combinations (Topic 805) and Consolidation (Topic 810): Determining the Accounting Acquirer in the Acquisition of a Variable Interest Entity.” This ASU revises current guidance for determining the accounting acquirer for a transaction effected primarily by exchanging equity interests in which the legal acquiree is a variable interest entity that meets the definition of a business. The amendments require an entity to consider the same factors that are currently required for determining which entity is the accounting acquirer in other acquisition transactions. This ASU is effective for annual reporting periods beginning after December 15, 2026, and interim reporting periods within those annual reporting periods. Early adoption is permitted in an interim or annual reporting period in which financial statements have not yet been issued (or made available for issuance). If an entity adopts ASU No. 2025-03 in an interim reporting period, it should adopt it as of the beginning of that interim reporting period or the beginning of the annual reporting period that includes that interim reporting period. An entity should apply ASU 2025-03 on a prospective basis to all business combinations that have an acquisition date that occurs on or after the date of initial application of ASU 2025-03. ASU 2025-03 is not expected to have a material impact on the financial statements of the Company.

Changes in Significant Accounting Policies

Significant accounting policies are presented in Note 1 to the consolidated financial statements included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2024. These policies, along with the disclosures presented in the other financial statement notes and, in this discussion, provide information on how significant assets and liabilities are valued in the consolidated financial statements and how those values are determined.

As of July 1, 2025, and as a result of the acquisition of Bancorp Financial, the Company amended its past due and nonaccrual loan policy disclosed in Note 1 of the December 31, 2024, Form 10-K to include a description of the retail non-real estate lending policy. The policy is amended as retail loans secured by collateral other than real estate that become past due 120 cumulative days from the contractual due date should generally be classified as a loss and charged off. In lieu of charging off the entire loan balance, loans with non-real estate collateral may be written down to the value of the collateral, less cost to sell, if repossession of collateral has occurred and collateral is in the Bank’s possession. Retail non-real estate loans covered by this policy include those disclosed within the other and powersport portfolios.

There are a variety of modification programs for the powersport portfolio (Holiday, Disaster, Military), of which most are defined within the contractual agreement. Exceptions are made outside of these programs in instances where there is a hardship. The Bank has elected to report the following as modifications to borrowers in financial difficulty: 1) modifications to borrowers who have filed bankruptcy, and 2) modifications for more than three months or more than four times in the last 12 months.

As a result of the acquisition, the Company also amended the policy for allowance for credit losses to incorporate the utilization of the vintage methodology on the powersport portfolio.

Subsequent Events

Dividends

On October 21, 2025, our Board of Directors declared a cash dividend of $0.07 per share of common stock payable on November 10, 2025, to stockholders of record as of October 31, 2025; dividends of $3.7 million will be paid to stockholders on November 10, 2025.