6-K

UNITED STATES 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 SECURITIES EXCHANGE ACT OF 1934

—————————

Dated November 21, 2025

Commission File Number: 001-35788

ARCELORMITTAL

(Translation of registrant’s name into English)

24-26, Boulevard d’Avranches

L-1160 Luxembourg

Grand Duchy of Luxembourg

(Address of principal executive office)

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 ☒        Form 40-F ☐

On November 21, 2025, ArcelorMittal published the press release attached hereto as Exhibit 99.1 and hereby incorporated by reference into this report on Form 6-K.

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.

ARCELORMITTAL

Date 21 November 2025

By: /s/ Henk Scheffer

Name: Henk Scheffer

Title: Company Secretary & Group Compliance & Data Protection Officer

Document

Exhibit 99.1

press release

ArcelorMittal cancels 77,809,772 treasury shares

21 November 2025, 11:00 CET

ArcelorMittal (the ‘Company’) announces that 77,809,772 shares treasury shares have been cancelled yesterday. Post cancellation, the Company still holds approximately 14.4 million treasury shares which will be used to service its commitments relating to its Long-Term Incentive Plan.

As a result of this cancellation, ArcelorMittal will have 775,000,000 shares in issue (compared to 852,809,772 before the cancellation).

Details on share buyback programs can be found at: https://corporate.arcelormittal.com/investors/equity-investors/share-buyback-program

With reference to article 14 of the Luxembourg law and the Grand Ducal regulation of 11 January 2008, on transparency requirements for issuers of securities (‘Transparency Law’), the total number of the Company’s voting rights and capital is available in the Luxembourg Stock Exchange’s electronic database OAM on www.bourse.lu and on the Company’s website under ‘Investors - Corporate Governance - Shareholding structure’.

ENDS

About ArcelorMittal

ArcelorMittal is one of the world’s leading integrated steel and mining companies with a presence in 60 countries and primary steelmaking operations in 14 countries. It is the largest steel producer in Europe, among the largest in the Americas, and has a growing presence in Asia through its joint venture AM/NS India. ArcelorMittal sells its products to a diverse range of customers including the automotive, engineering, construction and machinery industries, and in 2024 generated revenues of $62.4 billion, produced 57.9 million metric tonnes of crude steel and 42.4 million tonnes of iron ore. Our purpose is to produce smarter steels for people and planet. Steels made using innovative processes which use less energy, emit significantly less carbon and reduce costs. Steels that are cleaner, stronger and reusable.

Page 1 of 2

Steels for the renewable energy infrastructure that will support societies as they transform through this century. With steel at our core, our inventive people and an entrepreneurial culture at heart, we will support the world in making that change.

ArcelorMittal is listed on the stock exchanges of New York (MT), Amsterdam (MT), Paris (MT), Luxembourg (MT) and on the Spanish stock exchanges of Barcelona, Bilbao, Madrid and Valencia (MTS).

http://corporate.arcelormittal.com/

Page 2 of 2