Tenaris S.A.

Major Shareholding Notification • Dec 13, 2025

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

Weekly Report (December 8, 2025 – December 12, 2025) on the Second Tranche of Tenaris Share Buyback Program.

Luxembourg, December 12, 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 8, 2025 to (and including) December 12, 2025:

Date	Trading Venue	Shares Purchased	Weighted Average Price (EUR)	Purchases in EUR	Reference FX	Purchases in USD
08-dic-25	MTA	497,790	17.6893	8,805,557	1.1648	10,256,712
08-dic-25	CEUX	348,174	17.6900	6,159,198	1.1648	7,174,234
08-dic-25	TQEX	47,773	17.6897	845,090	1.1648	984,361
08-dic-25	AQXE	42,664	17.6911	754,773	1.1648	879,160
09-dic-25	MTA	501,957	17.5106	8,789,568	1.1625	10,217,873
09-dic-25	CEUX	359,428	17.5108	6,293,872	1.1625	7,316,626
09-dic-25	TQEX	48,625	17.5109	851,468	1.1625	989,831
09-dic-25	AQXE	43,407	17.5079	759,965	1.1625	883,460
10-dic-25	MTA	508,394	17.3553	8,823,330	1.1629	10,260,651
10-dic-25	CEUX	372,052	17.3542	6,456,665	1.1629	7,508,456
10-dic-25	TQEX	50,139	17.3540	870,112	1.1629	1,011,853
10-dic-25	AQXE	44,905	17.3526	779,219	1.1629	906,153
11-dic-25	MTA	525,251	17.3273	9,101,182	1.1642	10,595,596
11-dic-25	CEUX	393,679	17.3263	6,821,000	1.1642	7,941,009
11-dic-25	TQEX	53,577	17.3260	928,275	1.1642	1,080,698
11-dic-25	AQXE	45,104	17.3264	781,490	1.1642	909,811
12-dic-25	MTA	534,519	17.3035	9,249,050	1.1757	10,874,108
12-dic-25	CEUX	406,172	17.3015	7,027,385	1.1757	8,262,096
12-dic-25	TQEX	53,924	17.3004	932,907	1.1757	1,096,818
12-dic-25	AQXE	45,613	17.3031	789,246	1.1757	927,917
		4,923,147	17.4318	85,819,351		100,077,422

From December 8, 2025 to (and including) December 12, 2025, the Company has purchased a total of 4,923,147 ordinary shares for a total consideration of €85,819,351 equivalent to USD100,077,422.

As of December 12, 2025, the Company held in treasury 51,262,421 ordinary shares equal to 4.78% 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.