Tenaris S.A.

Declaration of Voting Results & Voting Rights Announcements • Jun 19, 2025

Giovanni Sardagna Tenaris 1-888-300-5432 www.tenaris.com

Tenaris provides information pursuant to Luxembourg Transparency Law

Luxembourg, June 18, 2025. - Tenaris S.A. (NYSE and Mexico: TS and EXM Italy: TEN) ("Tenaris", or the "Company") announced today that the Company's controlling shareholder, San Faustin S.A. ("San Faustin"), has notified the Company that, as a result of Tenaris's open market repurchases of own shares under its share buyback program publicly announced on May 27, 2025, San Faustin has passively crossed a voting rights threshold triggering a notice requirement under the Luxembourg Transparency Law.

On the date hereof, San Faustin informed the Company that, following repurchases of shares by Tenaris in the period from June 9 to June 13, 2025 (disclosed by Tenaris on June 13, 2025, in accordance with the EU Market Abuse Regulation), the 713,605,187 shares of the Company that San Faustin owns represent 66.82% of the Company's voting rights. As required by the Luxembourg Transparency Law, San Faustin has further provided information on its control chain, wich confirms that the Company's control structure disclosed on the Company's 2024 annual report remains unchanged.

Tenaris is a leading global supplier of steel tubes and related services for the world's energy industry and certain other industrial applications.