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SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

SCHEDULE 13G

UNDER THE SECURITIES EXCHANGE ACT OF 1934

(Name of Issuer)

(Title of Class of Securities)

(CUSIP Number)

(Date of Event Which Requires Filing of this Statement)

Check the appropriate box to designate the rule pursuant to which this Schedule is filed:

Rule 13d-1(b)

Rule 13d-1(c)

Rule 13d-1(d)

SCHEDULE 13D/A 0001429586 XXXXXXXX LIVE 11 Ordinary Shares, $1.00 par value per share 07/07/2025 false 0001190723 88031M109 Tenaris SA 26, BOULEVARD ROYAL, 4TH FLOOR LUXEMBOURG N4 L-2449 Fernando J. Mantilla 35227209600 26, Boulevard Royal, Ground Floor, Grand-Duchy of Luxembourg N4 L-2449 Y ROCCA & PARTNERS STICHTING ADMINISTRATIEKANTOOR AANDELEN SAN FAUSTIN OO N P7 0.00 713605187.00 0.00 713605187.00 713605187.00 N 67.5 HC Note to Row 4 (Source of funds): please refer to "Item 1 Comment" below. Note to Row 13 (Percent of class represented by amount in Row (11)): The percent of class figures set forth in this Amendment No. 11 are calculated based on 1,071,994,930 issued Ordinary Shares (as defined below), of which 15,396,773 were held by Tenaris S.A. as treasury stock as of July 4, 2025, as published on the website of Tenaris S.A. 0001429586 N SAN FAUSTIN S.A. OO N N4 0.00 713605187.00 0.00 713605187.00 713605187.00 N 67.5 CO Note to Row 4 (Source of funds): please refer to "Item 1 Comment" below. Note to Row 13 (Percent of class represented by amount in Row (11)): The percent of class figures set forth in this Amendment No. 11 are calculated based on 1,071,994,930 issued Ordinary Shares (as defined below), of which 15,396,773 were held by Tenaris S.A. as treasury stock as of July 4, 2025, as published on the website of Tenaris S.A. Y TECHINT HOLDINGS S.A R.L. OO N N4 713605187.00 0.00 713605187.00 0.00 713605187.00 N 67.5 CO Note to Row 4 (Source of funds): please refer to "Item 1 Comment" below. Note to Row 13 (Percent of class represented by amount in Row (11)): The percent of class figures set forth in this Amendment No. 11 are calculated based on 1,071,994,930 issued Ordinary Shares (as defined below), of which 15,396,773 were held by Tenaris S.A. as treasury stock as of July 4, 2025, as published on the website of Tenaris S.A. Ordinary Shares, $1.00 par value per share Tenaris SA 26, BOULEVARD ROYAL, 4TH FLOOR LUXEMBOURG N4 L-2449 This Amendment No. 11 amends and supplements the Schedule 13D originally filed on February 14, 2011 (this "Amendment No. 11"), as further amended by Amendments No. 1, No. 2, No. 3, No. 4, No. 5, No. 6, No. 7, No. 8, No. 9 and No. 10, on behalf of RP STAK, SAN FAUSTIN and TECHINT HOLDINGS (as defined thereunder), relating to the Ordinary Shares, par value $1 per share of Tenaris S.A. (the "Ordinary Shares"). This Amendment No. 11 reflects (i) an increase by 1.02% of the percent of class represented by the Ordinary Shares held by such Reporting Persons, from 66.52% to 67.54%, as reported on Rows 13 of the cover pages of this Schedule 13D, as a result of repurchases of Ordinary Shares made by Tenaris S.A. in the open market in the period from February 24, 2025 to March 4, 2025, under Tenaris S.A.'s 2024-2025 share buyback program publicly announced on November 10, 2024 and then in the period from June 9 until July 4, 2025, under Tenaris S.A.'s 2025-2026 share buyback program publicly announced on May 27, 2025; and (ii) certain changes in the composition of the board of directors or management of certain Reporting Persons. Except as specifically provided herein, this Amendment No. 11 does not modify any of the information previously reported on the Schedule 13D and its amendments. ROCCA & PARTNERS STICHTING ADMINISTRATIEKANTOOR AANDELEN SAN FAUSTIN ("RP STAK") Fascinatio Boulevard 764, 2909 VA Capelle aan den IJssel, The Netherlands. RP STAK is a private foundation (stichting) organized under the laws of The Netherlands. No person or group of persons controls RP STAK. SAN FAUSTIN S.A. ("SAN FAUSTIN") 26, Boulevard Royal, Ground Floor, L-2449 Luxembourg. SAN FAUSTIN is a societe anonyme (public limited liability company) organized under the laws of the Grand-Duchy of Luxembourg. RP STAK continues to control SAN FAUSTIN (i.e. it continues to have the ability to influence matters affecting, or submitted to a vote of the shareholders of SAN FAUSTIN, including the election of directors and the approval of certain corporate transactions and other matters concerning SAN FAUSTIN's policies). TECHINT HOLDINGS S.A R.L. ("TECHINT HOLDINGS") 26, Boulevard Royal, Ground Floor, L-2449 Luxembourg. TECHINT HOLDINGS is a societe a responsabilite limitee (private limited liability company) organized under the laws of the Grand-Duchy of Luxembourg. All of the shares of TECHINT HOLDINGS are held by SAN FAUSTIN. The name, residence or business address, present principal occupation or employment (and the name, principal business and address of any corporation or other organization in which such employment is conducted) and citizenship of each voting committee member, executive officer or director, as applicable, of each Reporting Person are set forth in Exhibit 99.1 hereto and is incorporated into this Item 2 by reference. During the last five years, none of the Reporting Persons, nor, to the knowledge of the Reporting Persons, none of the persons listed on Exhibit 99.1 hereto, has (i) been convicted in a criminal proceeding (excluding traffic violations or similar misdemeanors) or (ii) been a party to a civil proceeding of a judicial or administrative body of competent jurisdiction and as a result of such proceeding was or is subject to a judgment, decree or final order enjoining future violations of, or prohibiting or mandating activities subject to federal or state securities laws or finding any violation with respect to such laws. Information with respect to each of the Reporting Persons is given solely by such Reporting Person, and no Reporting Person assumes responsibility for the accuracy or completeness of information given by another Reporting Person. RP STAK. See items (7) through (11) and (13) on page 2 SAN FAUSTIN. See items (7) through (11) and (13) on page 3 TECHINT HOLDINGS. See items (7) through (11) and (13) on page 4 RP STAK. See items (7) through (11) and (13) on page 2 SAN FAUSTIN. See items (7) through (11) and (13) on page 3 TECHINT HOLDINGS. See items (7) through (11) and (13) on page 4 There have been no transactions in Ordinary Shares effected by the Reporting Persons or, to the best of the Reporting Person's knowledge, any person or entity identified on Exhibit 99.1 hereto, during the last 60 days. Not applicable. Not applicable. A Power of Attorney of ROCCA & PARTNERS STICHTING ADMINISTRATIEKANTOOR AANDELEN SAN FAUSTIN dated October 31st, 2023.* B Power of Attorney of SAN FAUSTIN S.A., dated September 28, 2023.* C Power of Attorney of TECHINT HOLDINGS S.a r.l., dated September 28, 2023.* D Exhibit 99.1 - Directors and Execetive Officers of Reporting Persons *Previously filed as an exhibit to the Amendement No. 5 to the Schedule 13D of Tenaris S.A. dated November 2, 2023 and incorporated by reference in this Amendment No. 11. ROCCA & PARTNERS STICHTING ADMINISTRATIEKANTOOR AANDELEN SAN FAUSTIN /s/ Fernando J. Mantilla Fernando J. Mantilla/Attorney-in-fact 07/07/2025 SAN FAUSTIN S.A. /s/ Fernando J. Mantilla Fernando J. Mantilla/Attorney-in-fact 07/07/2025 TECHINT HOLDINGS S.A R.L. /s/ Fernando J. Mantilla Fernando J. Mantilla/Attorney-in-fact 07/07/2025