Change in Certifying Accountants (Form 8-K)

ITEM 4.01 Changes in Registrant's Certifying Accountant

On October 31, 2025, the partners and professional staff of HORNE LLP ("HORNE"), which was engaged as the independent registered public accounting firm of the registrant, Catalyst Bancorp, Inc. (the "Company"), joined BDO USA, P.C. ("BDO"). As a result of this transaction, HORNE resigned as the Company's independent registered public accounting firm on October 31, 2025. On November 5, 2025, following the resignation of HORNE, the Company, through and with the approval of its Audit Committee, appointed BDO as its independent registered public accounting firm.

As previously reported on Form 8-K, HORNE was approved as the Company's independent registered public accounting firm on November 20, 2024 for the Company's fiscal year ending December 31, 2025. As a result of their resignation, HORNE has not issued reports on the financial statements of the Company.

During the period beginning on March 28, 2025 and through October 31, 2025, there were no disagreements between the Company and HORNE 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 HORNE, would have caused HORNE to make reference to the subject matter of the disagreements in connection with its audit reports on the Company's financial statements. During the period beginning on March 28, 2025 and through October 31, 2025, HORNE did not advise the Company of any of the matters specified in Item 304(a)(1)(v) of Regulation S-K.

The Company provided HORNE with a copy of this report on Form 8-K in accordance with Item 304(a) of Regulation S-K prior to its filing with the Securities and Exchange Commission and requested that HORNE furnish the Company with a letter addressed to the Securities and Exchange Commission 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 from HORNE is filed as Exhibit 16.1 hereto.

During the Company's two most recently completed fiscal years and through the date of engagement of BDO, neither the Company nor anyone on behalf of the Company consulted with BDO 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 was an important factor 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 (v), respectively, of Regulation S-K.

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