Tenaris S.A.

Transaction in Own Shares • Jan 4, 2026

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

Weekly Report (December 29, 2025 – January 2, 2026) on the Second Tranche of Tenaris Share Buyback Program.

Luxembourg, January 2, 2026. - Tenaris S.A. (NYSE and Mexico: TS and EXM Italy: TEN) ("Tenaris") announced today that pursuant to its Second Tranche of the USD1.2 billion Share Buyback Program announced on November 2, 2025, covering up to USD600 million to be executed in the open market, it has repurchased the following ordinary shares from December 29, 2025 to (and including) January 2, 2026:

Date	Trading Venue	Shares Purchased	Weighted Average Price (EUR)	Purchases in EUR	Reference FX	Purchases in USD
29-Dec-25	MTA	632,907	16.3859	10,370,751	1.17750	12,211,559
29-Dec-25	CEUX	423,694	16.3849	6,942,184	1.17750	8,174,421
29-Dec-25	TQEX	53,377	16.3850	874,582	1.17750	1,029,820
29-Dec-25	AQXE	52,847	16.3853	865,914	1.17750	1,019,614
30-Dec-25	MTA	633,977	16.4830	10,449,843	1.17670	12,296,330
30-Dec-25	CEUX	422,860	16.4821	6,969,621	1.17670	8,201,153
30-Dec-25	TQEX	51,342	16.4827	846,255	1.17670	995,788
30-Dec-25	AQXE	52,583	16.4833	866,741	1.17670	1,019,895
2-Jan-26	MTA	545,130	16.4563	8,970,823	1.17445	10,535,783
2-Jan-26	CEUX	362,289	16.4560	5,961,828	1.17445	7,001,869
2-Jan-26	TQEX	44,059	16.4563	725,048	1.17445	851,533
2-Jan-26	AQXE	44,960	16.4571	739,911	1.17445	868,989
		3,320,025	16.4407	54,583,501		64,206,753

From December 29, 2025 to (and including) January 2, 2026, the Company has purchased a total of 3,320,025 ordinary shares for a total consideration of €54,583,501 equivalent to USD64,206,753.

As of January 2, 2026, the Company held in treasury 62,328,172 ordinary shares equal to 5.81% 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.