Tenaris S.A.

Major Shareholding Notification • Dec 20, 2025

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

Weekly Report (December 15, 2025 – December 19, 2025) on the Second Tranche of Tenaris Share Buyback Program.

Luxembourg, December 19, 2025. - 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 15, 2025 to (and including) December 19, 2025:

Date	Trading Venue	Shares Purchased	Weighted Average Price (EUR)	Purchases in EUR	Reference FX	Purchases in USD
15-dic-25	MTA	535,192	17.2245	9,218,415	1.1739	10,821,036
15-dic-25	CEUX	393,420	17.2274	6,777,604	1.1739	7,955,890
15-dic-25	TQEX	51,585	17.2305	888,835	1.1739	1,043,359
15-dic-25	AQXE	46,237	17.2302	796,673	1.1739	935,174
16-dic-25	MTA	543,111	16.9763	9,220,015	1.1763	10,845,043
16-dic-25	CEUX	392,707	16.9767	6,666,869	1.1763	7,841,905
16-dic-25	TQEX	51,615	16.9759	876,211	1.1763	1,030,643
16-dic-25	AQXE	47,932	16.9776	813,770	1.1763	957,197
17-dic-25	MTA	554,876	16.9413	9,400,321	1.1770	11,064,178
17-dic-25	CEUX	403,224	16.9413	6,831,139	1.1770	8,040,250
17-dic-25	TQEX	51,544	16.9401	873,161	1.1770	1,027,710
17-dic-25	AQXE	48,798	16.9409	826,682	1.1770	973,005
18-dic-25	MTA	566,048	16.7532	9,483,115	1.1755	11,146,928
18-dic-25	CEUX	411,610	16.7538	6,896,032	1.1755	8,105,940
18-dic-25	TQEX	50,405	16.7536	844,465	1.1755	992,627
18-dic-25	AQXE	49,879	16.7543	835,688	1.1755	982,309
19-dic-25	MTA	597,146	16.2843	9,724,105	1.1727	11,403,457
19-dic-25	CEUX	435,667	16.2858	7,095,186	1.1727	8,320,524
19-dic-25	TQEX	53,631	16.2864	873,456	1.1727	1,024,302
19-dic-25	AQXE	52,366	16.2874	852,906	1.1727	1,000,203
		5,336,993	16.8250	89,794,646		105,511,681

From December 15, 2025 to (and including) December 19, 2025, the Company has purchased a total of 5,336,993 ordinary shares for a total consideration of €89,794,646 equivalent to USD105,511,681.

As of December 19, 2025, the Company held in treasury 56,599,414 ordinary shares equal to 5.28% 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.