Mannatech, Incorporated

Item 4.01 Changes in Registrant's Certifying Accountant. (a) Dismissal of Independent Registered Public Accounting Firm On October 15, 2026, the Audit Committee of the Board of Directors (the "Audit Committee") of Mannatech, Incorporated (the "Company") approved the dismissal of BDO USA, P.C. ("BDO") as the Company's independent registered public accounting firm, effective October 15, 2026. The Company notified BDO of the Audit Committee's decision on October 15, 2026. BDO's reports on the Company's consolidated financial statements as of and for the fiscal years ended December 31, 2025 and 2024 did not contain an adverse opinion or a disclaimer of opinion, and were not qualified or modified as to uncertainty, audit scope or accounting principles, except that BDO's report for the fiscal year ended December 31, 2025 contained an explanatory paragraph regarding substantial doubt about the Company's ability to continue as a going concern. During the fiscal years ended December 31, 2025 and 2024 and the subsequent interim period through October 15, 2026, there were no "disagreements" (as defined in Item 304(a)(1)(iv) of Regulation S-K and the related instructions) with BDO on any matter of accounting principles or practices, financial statement disclosure, or auditing scope or procedure which, if not resolved to BDO's satisfaction, would have caused BDO to make reference to the subject matter thereof in connection with its reports. During the same periods, there were no "reportable events" as defined in Item 304(a)(1)(v) of Regulation S-K. The Company provided BDO with a copy of the foregoing disclosures and requested that BDO furnish a letter addressed to the Securities and Exchange Commission stating whether it agrees with the statements above. A copy of BDO's letter, dated October 21, 2026, is filed as Exhibit 16.1 to this Amendment. (b) Engagement of New Independent Registered Public Accounting Firm On October 15, 2026, the Audit Committee approved the engagement of CBIZ CPAs P.C. ("CBIZ") as the Company's independent registered public accounting firm for the fiscal year ending December 31, 2026, beginning with the review of the Company's condensed consolidated financial statements for the quarter ended September 30, 2026. During the fiscal years ended December 31, 2025 and 2024 and the subsequent interim period through October 15, 2026, neither the Company nor anyone on its behalf consulted CBIZ regarding (i) the application of accounting principles to a specified transaction, completed or proposed, or the type of audit opinion that might be rendered on the Company's financial statements, and no written report or oral advice was provided that CBIZ concluded was an important factor considered by the Company in reaching a decision as to any accounting, auditing or financial reporting issue, or (ii) any matter that was the subject of a disagreement or a reportable event, each as defined in Item 304 of Regulation S-K.