SID 6-K

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM 6-K

Report of Foreign Private Issuer
Pursuant to Rule 13a-16 or 15d-16 of the

Securities Exchange Act of 1934

For the month of September, 2026

Commission File Number 1-14732

COMPANHIA SIDERÚRGICA NACIONAL

(Exact name of registrant as specified in its charter)

National Steel Company

(Translation of Registrant's name into English)

Av. Brigadeiro Faria Lima 3400, 20º andar
São Paulo, SP, Brazil
04538-132

(Address of principal executive office)

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

Indicate by check mark whether the registrant by furnishing the information contained in this Form is also thereby furnishing the information to the Commission pursuant to Rule 12g3-2(b) under the Securities Exchange Act of 1934.

Yes _______ No ___X____

MATERIAL FACT

Companhia Siderúrgica Nacional (“Company” or “CSN”) (B3: CSNA3; NYSE: SID), in compliance with article 157, paragraph 4º, of Law nº 6,404/1976 and CVM Resolution No. 44/2021, hereby informs its shareholders and the market in general that its Board of Directors has approved today the election of Mr. Benjamin Steinbruch to the position of Chairman of the Board of Directors of CSN. Starting September 3, 2026, Mr. Fabio Schvartsman will assume the position of Chief Executive Officer (CEO) of the Company.

The Company welcomes Mr. Fabio Schvartsman and wishes him great success in the execution of his new duties.

CSN will keep its shareholders and the market duly informed of any developments regarding this matter.

São Paulo, September 02, 2026.

SIGNATURE

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: September 2, 2026

FORWARD-LOOKING STATEMENTS

This press release may contain forward-looking statements. These statements are statements that are not historical facts, and are based on management's current view and estimates of future economic circumstances, industry conditions, company performance and financial results. The words "anticipates", "believes", "estimates", "expects", "plans" and similar expressions, as they relate to the company, are intended to identify forward-looking statements. Statements regarding the declaration or payment of dividends, the implementation of principal operating and financing strategies and capital expenditure plans, the direction of future operations and the factors or trends affecting financial condition, liquidity or results of operations are examples of forward-looking statements. Such statements reflect the current views of management and are subject to a number of risks and uncertainties. There is no guarantee that the expected events, trends or results will actually occur. The statements are based on many assumptions and factors, including general economic and market conditions, industry conditions, and operating factors. Any changes in such assumptions or factors could cause actual results to differ materially from current expectations.