FORM 6 - K

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

Report of Foreign Private Issuer

Pursuant to Rule 13a - 16 or 15d - 16 of

the Securities Exchange Act of 1934

As of September 30, 2025

TENARIS, S.A.

(Translation of Registrant's name into English)

26, Boulevard Royal, 4th floor

L-2449 Luxembourg

(Address of principal executive offices)

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

Form 20-F  ✓  Form 40-F       

The attached material is being furnished to the Securities and Exchange Commission pursuant to Rule 13a-16 and Form 6-K under the Securities Exchange Act of 1934, as amended. This report contains Tenaris’s Press Release announcing Tenaris completes USD600 million First Tranche of its Share Buyback Program.

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 30, 2025

Tenaris, S.A.

By: /s/ Giovanni Sardagna

Giovanni Sardagna

Investor Relations Officer

Giovanni Sardagna

Tenaris

1-888-300-5432

www.tenaris.com

Tenaris completes USD600 million First Tranche of its Share Buyback Program.

Luxembourg, September 30, 2025. - Tenaris S.A. (NYSE and Mexico: TS and EXM Italy: TEN) (“Tenaris”) announced today the completion of the first USD600 million tranche of its USD1.2 billion Share Buyback Program announced on June 6, 2025 (the “Program”).

During this first tranche, which ran from June 9, 2025, to (and including) September 30, 2025, the Company purchased a total of 33,059,955 ordinary shares, representing 3.08% of its total issued share capital, for a total consideration of €516,588,880, or approximately USD600 million.

As of September 30, 2025, the 33,059,955 ordinary shares that the Company bought in the first tranche of the Program are held in treasury.

Tenaris intends to cancel all treasury shares purchased under the Program in due course.

Details of the above transactions are available on Tenaris’s corporate website under the Share Buyback Program Section https://ir.tenaris.com/share-buyback-program.

Some of the statements contained in this press release are “forward-looking statements”. Forward-looking statements are based on management’s current views and assumptions and involve known and unknown risks that could cause actual results, performance or events to differ materially from those expressed or implied by those statements. These risks include but are not limited to risks arising from uncertainties as to future oil and gas prices and their impact on investment programs by oil and gas companies.

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