Tenaris S.A.

Transaction in Own Shares • Sep 27, 2025

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

Weekly Report (September22, 2025 – September 26, 2025) on the First Tranche of Tenaris Share Buyback Program.

Luxembourg, September 26, 2025. - Tenaris S.A. (NYSE and Mexico: TS and EXM Italy: TEN) ("Tenaris") announced today that pursuant to its First Tranche of the USD1.2 billion Share Buyback Program announced on June 6, 2025, covering up to USD600 million to be executed in the open market, it has repurchased the following ordinary shares from September 22, 2025 to (and including) September 26, 2025:

Date	Trading Venue	Shares Purchased	Weighted Average Price (EUR)	Purchases in EUR	Reference F X	Purchases in USD
22-sep-25	MTAA	502,533	14.7730	7,423,920	1.1772	8,739,439
22-sep-25	CEUX	278,000	14.7713	4,106,421	1.1772	4,834,079
22-sep-25	TQEX	58,000	14.7641	856,318	1.1772	1,008,057
22-sep-25	AQEU	57,000	14.7556	841,069	1.1772	990,107
23-sep-25	MTAA	235	14.8450	3,489	1.1796	4,115
23-sep-25	CEUX	899	14.8350	13,337	1.1796	15,732
23-sep-25	AQEU	1,431	14.8450	21,243	1.1796	25,058
24-sep-25	MTAA	897	15.0600	13,509	1.1743	15,863
24-sep-25	CEUX	867	15.0600	13,057	1.1743	15,333
24-sep-25	TQEX	455	15.0600	6,852	1.1743	8,047
25-sep-25	MTAA	483,000	14.8717	7,183,031	1.1677	8,387,266
25-sep-25	CEUX	308,000	14.8696	4,579,837	1.1677	5,347,646
25-sep-25	TQEX	62,000	14.8624	921,469	1.1677	1,075,953
25-sep-25	AQEU	60,000	14.8624	891,744	1.1677	1,041,245
26-sep-25	MTAA	482,206	15.1353	7,298,332	1.1693	8,533,575
26-sep-25	CEUX	312,560	15.1344	4,730,408	1.1693	5,531,030
26-sep-25	TQEX	62,480	15.1248	944,998	1.1693	1,104,938
26-sep-25	AQEU	53,010	15.1477	802,980	1.1693	938,884
		2,723,573	14.9260	40,652,013		47,616,368

From September 22, 2025 to (and including) September 26, 2025, the Company has purchased a total of 2,723,573 ordinary shares for a total consideration of €40,652,013, equivalent to USD47,616,368.

As of September 26, 2025, the Company held in treasury 32,401,871 ordinary shares equal to 3.02% of the total issued share capital.

Tenaris intends to cancel treasury shares purchased under the Programs 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.