6-K

U.S. SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM 6-K

REPORT OF FOREIGN PRIVATE ISSUER

PURSUANT TO RULE 13a-16 OR 15d-16 UNDER THE

SECURITIESEXCHANGE ACT OF 1934

Dated February 23, 2026

Commission File Number 1-14878

GERDAU S.A.

(Translation of Registrant’s Name into English)

Av. Dra. Ruth Cardoso, 8,501 – 8° andar

São Paulo, São Paulo - Brazil CEP 05425-070

(Address of principal executive offices)

Indicate by check mark whether the registrant files or will file annual reports under cover of Form 20-F or Form 40-F.

Form 20-F  x           Form 40-F  ¨

Exhibit Index

SIGNATURES

Pursuant to the requirements of the Securities Exchange Act of 1934, the registrant has duly caused this Report to be signed on its behalf by the undersigned, thereunto duly authorized.

Date: February 23, 2026

Exhibit 99.1

NOTICE TO SHAREHOLDERS

PAYMENT OF DIVIDENDS

We would like to inform our Shareholders that Gerdau S.A. and Metalúrgica Gerdau S.A. (collectively, the “Companies”) Boards of Directors approved, on this date, the payment of Dividends as an anticipation of the minimum payment for the current fiscal year of 2025. The amount will be paid according to the dates listed bellow:

The payments will be made by the share depository institution, BTG Pactual Serviços Financeiros S/A DTVM, through automatic credit for those shareholders who have provided their CPF/CNPJ registration number (Tax ID) and respective bank account. Additional information can be obtained through [email protected].

The dividends not claimed within a period of 3 (three) years, counting from the date they were made available to the shareholders, will prescribe and revert in favor of the Companies (Brazilian law 6.404/76, article 287, section II, item a).

São Paulo, February 23, 2026.

Rafael Dorneles Japur

Vice President and Investor Relations Officer

Exhibit 99.2

GERDAU S.A.

Corporate Tax ID (CNPJ/MF): 33.611.500/0001-19

Registry (NIRE): 35300520696

MATERIAL FACT

GERDAU S.A. (B3: GGBR / NYSE: GGB) ("Company") informs its shareholders and the market in general that the Board of Directors, at a meeting held on this date, approved the cancellation of 418,800 common shares (GGBR3) and 7,700,000 preferred shares (GGBR4) issued by the Company, with no par value and no reduction in the value of the capital stock. As a result of this cancellation of shares, the Company's capital stock is now divided into 717,363,819 common shares and 1,275,397,330 preferred shares, with no par value. The respective amendment to article 4 of the Bylaws, to reflect the new number of shares, shall be resolved at a Shareholders' Meeting to be called in due course.

In addition, the Board of Directors approved a new share buyback program issued by the Company ("2026 Buyback Program"), as detailed below:

Program Objectives: (i) maximize value creation for shareholders in the long term through efficient management of its capital structure meeting the needs of the long-term incentive programs of the Company and its subsidiaries; (ii) maintain shares in treasury; (iii) cancellation; or (iv) subsequently sell the shares in the market.

Number of shares to be acquired: up to 55,000,000 preferred shares, representing approximately 4.4% of the outstanding preferred shares (GGBR4) and/or preferred shares (GGB)-backed ADRs and up to 1,441,120 common shares, representing approximately 10% of the outstanding common shares (GGBR3).

Acquisition period: from February 24, 2026, with a maximum duration of 18 (eighteen) months, that is, until August 24, 2027, inclusive.

Further information on the 2026 Buyback Program, as required by Annex G of CVM Resolution 80, of March 29, 2022, can be found attached to the minutes of the Board of Directors Meeting, which is available on the websites of the Company’s Investor Relations (https://ri.gerdau.com/), of the CVM (https://www.gov.br/cvm/pt-br) and of B3 (https://www.b3.com.br/pt_br/).

São Paulo, February 23, 2026.

Rafael Dorneles Japur

Vice-President and

Investor Relations Officer