Change in Certifying Accountants (Form 8-K)

Item 4.01 Changes in Registrant's Certifying Accountant

(a) Dismissal of Previous Independent Registered Public Accounting Firm

On June 17, 2026, Investar Holding Corporation (the "Company"), through and with the approval of the audit committee of the board of directors of the Company (the "Audit Committee"), dismissed BDO USA, P.C. ("BDO") as the Company's independent registered public accounting firm.

Prior to BDO's engagement, the Company's financial statements were audited by HORNE LLP ("Horne"). On November 1, 2025, the partners and professional staff of Horne joined BDO. As a result of this transaction, Horne resigned as the Company's independent registered public accounting firm on November 1, 2025, and on November 3, 2025, the Company appointed BDO as its independent registered public accounting firm.

The reports of BDO (formerly Horne) regarding the Company's financial statements for the fiscal years ended December 31, 2025 and 2024 did not contain any adverse opinion or disclaimer of opinion and were not qualified or modified as to uncertainty, audit scope or accounting principles.

During the Company's fiscal years ended December 31, 2025 and 2024, and the interim period from the end of the most recently completed fiscal year through June 17, 2026, the date of dismissal, there were (a) no disagreements, as defined in Item 304(a)(1)(iv) of Regulation S-K and the related instructions thereto, between the Company and BDO on any matter of accounting principles or practices, financial statement disclosure, or auditing scope or procedure, which disagreements, if not resolved to the satisfaction of BDO, would have caused BDO to make reference to the subject matter of the disagreements in connection with its audit reports on the Company's financial statements, and (b) no reportable events as defined in Item 304(a)(1)(v) of Regulation S-K.

The Company provided BDO with a copy of this Current Report on Form 8-K prior to its filing with the Securities and Exchange Commission ("SEC") and requested that BDO furnish the Company with a letter addressed to the SEC stating whether it agrees with the above statements and, if it does not agree, the respects in which it does not agree. A copy of the letter furnished by BDO, dated June 19, 2026, is filed as Exhibit 16.1 to this Current Report on Form 8-K.

(b) Appointment of New Independent Registered Public Accounting Firm

On June 17, 2026, the Audit Committee engaged Wipfli LLP ("Wipfli") to serve as its independent registered public accounting firm for the fiscal year ending December 31, 2026.

During the Company's fiscal years ended December 31, 2025 and 2024, and during the interim period from the end of the most recently completed fiscal year through June 17, 2026, the date of engagement of Wipfli, neither the Company nor anyone on behalf of the Company consulted with Wipfli regarding (a) the application of accounting principles to a specified transaction, either completed or proposed, or the type of audit opinion that might be rendered on the Company's financial statements as to which the Company received a written report or oral advice that Wipfli concluded was an important factor considered by the Company in reaching a decision on any accounting, auditing or financial reporting issue; or (b) any matter that was the subject of a disagreement or a reportable event as defined in Items 304(a)(1)(iv), and the related instructions thereto, and (v), respectively, of Regulation S-K.