FORM 6 - K

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

Report of Foreign Private Issuer

Pursuant to Rule 13a - 16 or 15d - 16 of

the Securities Exchange Act of 1934

As of May 6, 2026

TENARIS, S.A.

(Translation of Registrant's name into English)

26, Boulevard Royal, 4th floor

L-2449 Luxembourg

(Address of principal executive offices)

Indicate by check mark whether the registrant files or will file annual reports under cover Form 20-F or 40-F.

Form 20-F Ö Form 40-F __

The attached material is being furnished to the Securities and Exchange Commission pursuant to Rule 13a-16 and Form 6-K under the Securities Exchange Act of 1934, as amended. This report contains Tenaris S.A. Consolidated Condensed Interim Financial Statements for the three-month period ended March 31, 2026.

SIGNATURE

Pursuant to the requirements of the Securities Exchange Act of 1934, the Registrant has duly caused this report to be signed on its behalf by the undersigned, thereunto duly authorized.

Date: May 6, 2026

Tenaris, S.A.

By: /s/ Giovanni Sardagna

Giovanni Sardagna

Investor Relations Officer

Consolidated Condensed Interim Financial Statements For the three-month period ended March 31, 2026 - all amounts in thousands of U.S. dollars, unless otherwise stated

CONSOLIDATED CONDENSED INTERIM INCOME STATEMENTS

^(*) Number of outstanding shares as of March 31, 2026, and 2025, was 1,009,639,756 and 1,071,994,930, respectively.

^(**) Each ADS equals two shares.

The accompanying notes are an integral part of these Consolidated Condensed Interim Financial Statements.

These Consolidated Condensed Interim Financial Statements should be read in conjunction with our audited Consolidated Financial Statements and notes for the fiscal year ended December 31, 2025.

Consolidated Condensed Interim Financial Statements For the three-month period ended March 31, 2026 - all amounts in thousands of U.S. dollars, unless otherwise stated

CONSOLIDATED CONDENSED INTERIM STATEMENTS OF OTHER COMPREHENSIVE INCOME

The accompanying notes are an integral part of these Consolidated Condensed Interim Financial Statements.

These Consolidated Condensed Interim Financial Statements should be read in conjunction with our audited Consolidated Financial Statements and notes for the fiscal year ended December 31, 2025.

Consolidated Condensed Interim Financial Statements For the three-month period ended March 31, 2026 - all amounts in thousands of U.S. dollars, unless otherwise stated

CONSOLIDATED CONDENSED INTERIM STATEMENTS OF FINANCIAL POSITION

The accompanying notes are an integral part of these Consolidated Condensed Interim Financial Statements.

These Consolidated Condensed Interim Financial Statements should be read in conjunction with our audited Consolidated Financial Statements and notes for the fiscal year ended December 31, 2025.

Consolidated Condensed Interim Financial Statements For the three-month period ended March 31, 2026 - all amounts in thousands of U.S. dollars, unless otherwise stated

CONSOLIDATED CONDENSED INTERIM STATEMENTS OF CHANGES IN EQUITY

⁽¹⁾ The Company has an authorized share capital of a single class of 2.5 billion shares having a nominal value of USD1.00 per share. As of March 31, 2026, there were 1,071,994,930 shares issued. All issued shares are fully paid.

⁽²⁾ As of March 31, 2026, the Company held 62,355,174 treasury shares, and there were 1,009,639,756 outstanding shares. For more information see note 23.

⁽³⁾ Other reserves include mainly the result of transactions with non-controlling interests that do not result in a loss of control, the remeasurement of post-employment benefit obligations, the changes in value of cash flow hedges and in financial instruments measured at fair value through other comprehensive income and the changes in the share buyback program liability.

⁽⁴⁾ The restrictions to the distribution of profits and payment of dividends according to Luxembourg Law are disclosed in note 18.

The accompanying notes are an integral part of these Consolidated Condensed Interim Financial Statements.

These Consolidated Condensed Interim Financial Statements should be read in conjunction with our audited Consolidated Financial Statements and notes for the fiscal year ended December 31, 2025.

Consolidated Condensed Interim Financial Statements For the three-month period ended March 31, 2026 - all amounts in thousands of U.S. dollars, unless otherwise stated

⁽¹⁾ The Company had an authorized share capital of a single class of 2.5 billion shares having a nominal value of USD1.00 per share. As of March 31, 2025, there were 1,162,757,528 shares issued. All issued shares are fully paid.

⁽²⁾ As of March 31, 2025, the Company held 90,762,598 treasury shares, and there were 1,071,994,930 outstanding shares. For more information see note 23.

⁽³⁾ Other reserves include mainly the result of transactions with non-controlling interests that do not result in a loss of control, the remeasurement of post-employment benefit obligations, the changes in value of cash flow hedges and in financial instruments measured at fair value through other comprehensive income and the changes in the share buyback program liability.

⁽⁴⁾ The restrictions to the distribution of profits and payment of dividends according to Luxembourg Law are disclosed in note 18.

The accompanying notes are an integral part of these Consolidated Condensed Interim Financial Statements.

These Consolidated Condensed Interim Financial Statements should be read in conjunction with our audited Consolidated Financial Statements and notes for the fiscal year ended December 31, 2025.

Consolidated Condensed Interim Financial Statements For the three-month period ended March 31, 2026 - all amounts in thousands of U.S. dollars, unless otherwise stated

CONSOLIDATED CONDENSED INTERIM STATEMENTS OF CASH FLOWS

^(*) Changes in working capital do not include non-cash movements due to the variations in the exchange rates used by subsidiaries with functional currencies different from the U.S. dollar for an amount of $9.4 million for the three-month period ended March 31, 2026 and $(14.5) million for the three-month period ended March 31, 2025.

^(**) For the three-month period ended March 31, 2026, mainly related to the acquisition of the oilfield division of AllTorque. For more information see note 24.

The accompanying notes are an integral part of these Consolidated Condensed Interim Financial Statements.

These Consolidated Condensed Interim Financial Statements should be read in conjunction with our audited Consolidated Financial Statements and notes for the fiscal year ended December 31, 2025.

Consolidated Condensed Interim Financial Statements For the three-month period ended March 31, 2026 - all amounts in thousands of U.S. dollars, unless otherwise stated

NOTES TO THE CONSOLIDATED CONDENSED INTERIM FINANCIAL STATEMENTS

Consolidated Condensed Interim Financial Statements For the three-month period ended March 31, 2026 - all amounts in thousands of U.S. dollars, unless otherwise stated

NOTES TO THE CONSOLIDATED CONDENSED INTERIM FINANCIAL STATEMENTS

Tenaris S.A. (the "Company") was established as a public limited liability company (société anonyme) under the laws of the Grand-Duchy of Luxembourg on December 17, 2001. The Company holds, either directly or indirectly, controlling interests in various subsidiaries in the steel pipe manufacturing and distribution businesses. References in these Consolidated Condensed Interim Financial Statements to “Tenaris” refer to Tenaris S.A. and its consolidated subsidiaries. A list of the Company’s principal subsidiaries is included in note 33 to the Company’s audited Consolidated Financial Statements for the year ended December 31, 2025.

The Company’s shares trade on the Italian Stock Exchange and the Mexican Stock Exchange, and its American Depositary Securities (“ADS”) trade on the New York Stock Exchange.

These Consolidated Condensed Interim Financial Statements were approved for issuance by the Company’s Board of Directors on May 6, 2026.

These Consolidated Condensed Interim Financial Statements have been prepared in accordance with IAS 34, “Interim Financial Reporting” as issued by the International Accounting Standards Board (“IASB”) and as adopted by the European Union (“EU”). The accounting policies used in the preparation of these Consolidated Condensed Interim Financial Statements are consistent with those used in the audited Consolidated Financial Statements for the year ended December 31, 2025. These Consolidated Condensed Interim Financial Statements should be read in conjunction with the audited Consolidated Financial Statements for the year ended December 31, 2025, which have been prepared in accordance with International Financial Reporting Standards (“IFRS”) Accounting Standards as issued by the IASB and in conformity with IFRS as adopted by the EU.

The preparation of Consolidated Condensed Interim Financial Statements requires management to make certain accounting estimates and assumptions that might affect the reported amounts of assets and liabilities and the disclosure of contingent liabilities as of the reporting dates, and the reported amounts of revenues and expenses for the reported periods. Actual results may differ from these estimates. The main areas involving significant estimates or judgments are impairment of long-lived assets; impairment of investments in associates; income taxes -including recoverability of deferred tax assets-; allowance for obsolescence of inventory; contingencies; allowance for trade receivables; post-employment and other long-term benefits; business combinations; useful lives of property, plant and equipment and other long-lived assets and fair value estimation of certain financial instruments. During the period there were no material changes in the significant accounting estimates and judgements.

Tenaris carefully assesses the potential impact of climate change and energy transition on its business and the risks to its markets and its tangible and intangible assets and adapts its business strategy accordingly. These events did not impact materially management judgments and estimates used in the preparation of these Consolidated Condensed Interim Financial Statements. For further information, see note 36 to our audited Consolidated Financial Statements for the year ended December 31, 2025.

Material intercompany transactions, balances and unrealized gains (losses) on transactions between Tenaris’s subsidiaries have been eliminated in consolidation. However, since the functional currency of some subsidiaries is their respective local currency, some financial gains (losses) arising from intercompany transactions are generated. These are included in the Consolidated Condensed Interim Income Statements under Other financial results, net.

There were no significant changes in valuation techniques during the period and there have been no changes in any risk management policies since the year ended December 31, 2025.

If necessary, comparative amounts have been reclassified to conform to changes in presentation in the current period.

None of the accounting pronouncements applicable after December 31, 2025, and as of the date of these Consolidated Condensed Interim Financial Statements had a material effect on the Company’s financial condition or result of its operations.

Consolidated Condensed Interim Financial Statements For the three-month period ended March 31, 2026 - all amounts in thousands of U.S. dollars, unless otherwise stated

Reportable operating segments

(All amounts in millions of U.S. dollars)

There are no material differences between IFRS and management views in total revenues.

The differences between operating income under the IFRS and management views are mainly related to the cost of goods sold, reflecting the effect of raw materials prices variations on the valuation of the replacement cost considered for management view compared to IFRS cost calculated at historical cost on a FIFO basis, and other timing differences. For more information see note II.C “Segment information” in the Company’s audited Consolidated Financial Statements for the year ended December 31, 2025.

The main differences in net income under the IFRS and management views arise from the impact of functional currencies on financial result, deferred income taxes as well as the equity in earnings of non-consolidated companies.

Geographical information

Allocation of net sales to geographical information is based on the final destination of the products sold.

Consolidated Condensed Interim Financial Statements For the three-month period ended March 31, 2026 - all amounts in thousands of U.S. dollars, unless otherwise stated

There are no revenues from external customers attributable to the Company’s country of incorporation (Luxembourg). The principal countries from which the Company derives its revenues are USA, Argentina, Canada, Saudi Arabia, Mexico, United Arab Emirates and Brazil.

No single customer comprised more than 10% of Tenaris’s net sales in the three-month periods ended March 31, 2026, and 2025.

Revenue is mainly recognized at a point in time to direct customers, when control has been transferred and there is no unfulfilled performance obligation that could affect the acceptance of the product by the customer. In the three-month periods ended March 31, 2026, and 2025, revenues related to governmental institutions represented approximately 25% and 28%, respectively.

Tubes segment revenues by market:

(All amounts in millions of U.S. dollars)

The table above includes revenues from services performed on third party tubes of $108.7 million and $101.3 million for the three-month periods ended March 31, 2026, and 2025, respectively.

^(*) For the three-month period ended March 31, 2026, related to the purchase price allocation arising from the acquisition of a scrap processing business in Beaver Falls, Pennsylvania. For more information see note 24.

Consolidated Condensed Interim Financial Statements For the three-month period ended March 31, 2026 - all amounts in thousands of U.S. dollars, unless otherwise stated

Provision for the ongoing litigation related to the acquisition of participation in Usiminas: This item relates to the provision described in note 18, without reflecting any net foreign exchange result associated thereto.

Consolidated Condensed Interim Financial Statements For the three-month period ended March 31, 2026 - all amounts in thousands of U.S. dollars, unless otherwise stated

Finance income: For the three-month period ended March 31, 2026, includes $10.9 million of interest related to instruments carried at FVTPL and includes $16.7 million of interest related to instruments carried at FVTOCI.

For the three-month period ended March 31, 2025, includes $6.3 million of interest related to instruments carried at FVTPL and includes $24.8 million of interest related to instruments carried at FVTOCI.

Other: For the three-month period ended March 31, 2025, includes a loss of approximately $15.8 million related to fees paid in connection with a collection involving the Company’s Mexican subsidiary.

Tenaris is within the scope of the OECD Pillar Two model rules. Pillar Two legislation was adopted in Luxembourg, the jurisdiction in which the Company is incorporated, and came into effect as from January 1, 2024. Tenaris applies the exception regarding the recognition and disclosure of deferred tax assets and liabilities related to Pillar Two income taxes, as provided in the amendments to IAS 12 issued in May 2023.

In the three-month period ended March 31, 2026 and 2025, Tenaris recognized an estimated current tax expense related to Pillar Two, amounting to $1.6 million and $3.6 million, respectively.

Consolidated Condensed Interim Financial Statements For the three-month period ended March 31, 2026 - all amounts in thousands of U.S. dollars, unless otherwise stated

On February 18, 2026, the Company´s board of directors proposed, for the approval of the Annual General Shareholders' meeting to be held on May 12, 2026, the payment of an annual dividend of $0.89 per outstanding share ($1.78 per ADS), or approximately $0.9 billion, which includes the interim dividend of $0.29 per outstanding share ($0.58 per ADS) or approximately $0.3 billion, paid on November 26, 2025. If the annual dividend is approved by the shareholders, a dividend of $0.60 per outstanding share ($1.20 per ADS), or approximately $0.6 billion will be paid on May 20, 2026, with record date on May 19, 2026. These Consolidated Condensed Interim Financial Statements do not reflect this dividend.

On May 6, 2025, the Company’s shareholders approved an annual dividend in the amount of $0.83 per outstanding share ($1.66 per ADS). The amount approved by the shareholders included the interim dividend previously paid on November 20, 2024, in the amount of $0.27 per outstanding share ($0.54 per ADS). The remaining balance, amounting to $0.56 per outstanding share ($1.12 per ADS), was paid on May 21, 2025, for an amount of approximately $0.6 billion. In the aggregate, the interim dividend paid in November 2024 and the balance paid in May 2025 amounted to approximately $0.9 billion.

^(*) For the three-month period ended March 31, 2026, related to the acquisition of the oilfield division of AllTorque and the purchase price allocation arising from the acquisition of a scrap processing business in Beaver Falls, Pennsylvania. For more information see note 24.

The Company’s Brazilian subsidiary Confab Industrial S.A. (“Confab”) holds certain real estate assets, with a carrying value of $33.8 million, that are subject to a judicial mortgage aimed at securing the indemnification potentially payable to Companhia Siderúrgica Nacional (“CSN") under a lawsuit brough by CSN against Confab and other related companies. The litigation is currently pending, and no amount is currently owed by Confab. See note 18 “Contingencies, commitments and restrictions to the distribution of profits - Contingencies - CSN claims relating to the January 2012 acquisition of Usiminas”.

The Company’s Saudi Arabian subsidiary, Global Pipe Company (“GPC”), holds certain assets with a carrying value of $49.7 million that are pledged as security for current borrowings. Tenaris holds an indirect participation of 27.6% in GPC through its subsidiary, Saudi Steel Pipe Company (“SSPC”).

Consolidated Condensed Interim Financial Statements For the three-month period ended March 31, 2026 - all amounts in thousands of U.S. dollars, unless otherwise stated

^(*) For the three-month period ended March 31, 2026, related to the acquisition of the oilfield division of AllTorque and the purchase price allocation arising from the acquisition of a scrap processing business in Beaver Falls, Pennsylvania. For more information see note 24.

Right-of-use assets, net evolution

Right-of-use assets, net by underlying category

Depreciation of right-of-use assets was mainly included in the Tubes segment.

Lease liabilities evolution

^(*) For the three-month period ended March 31, 2026, includes repayments of $15.5 million in capital and $1.1 million of interest.

For the three-month period ended March 31, 2025, includes repayments of $14.7 million in capital and $1.3 million of interest.

Consolidated Condensed Interim Financial Statements For the three-month period ended March 31, 2026 - all amounts in thousands of U.S. dollars, unless otherwise stated

As of March 31, 2026, the amount of remaining payments with maturities of less than 1 year, between 2 and 5 years and more than 5 years was approximately 34%, 41% and 25%, respectively.

As of December 31, 2025, the amount of remaining payments with maturities of less than 1 year, between 2 and 5 years and more than 5 years was approximately 34%, 41%, and 25%, respectively.

As of March 31, 2026, Other Investments – current includes financial assets subject to lending agreements with financial institutions for a total amount of $100.7 million. Under applicable contractual terms, Tenaris retains substantially all the risks and rewards of ownership of the financial assets and has not received any collateral in connection to them. The fee received is recognized as a gain within Finance income, as interest income.

Other derivatives include contracts which are designated to hedge positions other than borrowings and investments.

Consolidated Condensed Interim Financial Statements For the three-month period ended March 31, 2026 - all amounts in thousands of U.S. dollars, unless otherwise stated

The following table illustrates the three hierarchical levels for valuing financial instruments at fair value and those measured at amortized cost as of March 31, 2026, and December 31, 2025.

^(*) Includes liability related to the share buyback program.

Certain non-financial assets and liabilities were included in the above tables to allow reconciliation with the Consolidated Condensed Interim Statements of Financial Position.

Due to their short time nature, the carrying amounts of trade receivables, trade payables, other financial receivables, other financial liabilities and other investments are considered to be similar to their fair values.

Consolidated Condensed Interim Financial Statements For the three-month period ended March 31, 2026 - all amounts in thousands of U.S. dollars, unless otherwise stated

There were no transfers between levels during the period.

The fair value of financial instruments traded in active markets is based on quoted market prices at the reporting date. A market is regarded as active if quoted prices are readily and regularly available from an exchange, dealer, broker, industry group, pricing service, or regulatory agency, and those prices represent actual and regularly occurring market transactions on an arm’s length basis. The quoted market price used for financial assets held by Tenaris is the current bid price. These instruments are included in Level 1 and comprise primarily corporate and sovereign debt securities.

The fair value of financial instruments that are not traded in an active market (such as certain debt securities, certificates of deposits with original maturity of more than three months, forward and interest rate derivative instruments) is determined by using valuation techniques which maximize the use of observable market data when available and rely as little as possible on entity specific estimates. If all significant inputs required to value an instrument are observable, the instrument is included in Level 2. Tenaris values its assets and liabilities included in this level using bid prices, interest rate curves, broker quotations, current exchange rates, forward rates and implied volatilities obtained from market contributors as of the valuation date.

The fair value of all outstanding derivatives is determined using specific pricing models that include inputs that are observable in the market or can be derived from or corroborated by observable data. The fair value of forward foreign exchange contracts is calculated as the net present value of the estimated future cash flows in each currency, based on observable yield curves, converted into U.S. dollars at the spot rate of the valuation date.

If one or more of the significant inputs are not based on observable market data, the instruments are included in Level 3. Tenaris values its assets and liabilities in this level using management assumptions which reflect the Company’s best estimate on how market participants would price the asset or liability at measurement date. As of December 31, 2025, main balances in this level included a liability related to the shares to be settled under the share buyback program which was concluded during the three-month period ended March 31, 2026. Unobservable inputs related to this balance consider assumptions regarding average purchase prices of previous periods, and management's past experience related to the conclusion of the share buyback program itself. A reasonable change in the inputs used would have not affected the fair value of the liability materially.

Borrowings are comprised primarily of fixed rate debt and variable rate debt with a short-term portion where interest has already been fixed. They are classified under other financial liabilities and measured at their amortized cost. Tenaris estimates that the fair value (level 2) of its main borrowings is approximately 99.4% of its carrying amount including interests accrued as of March 31, 2026, as compared with 99.5% as of December 31, 2025. Fair values were calculated using standard valuation techniques for floating rate instruments and comparable market rates for discounting cash flows.

This note supplements and should be read in conjunction with note 14 “Investments in non-consolidated companies” to the Company’s audited Consolidated Financial Statements for the year ended December 31, 2025.

Consolidated Condensed Interim Financial Statements For the three-month period ended March 31, 2026 - all amounts in thousands of U.S. dollars, unless otherwise stated

Ternium S.A. (“Ternium”) is a steel producer with production facilities in Mexico, Argentina, Brazil, Colombia, United States and Guatemala and is one of Tenaris’s suppliers of round steel bars and flat steel products for its pipes business.

As of March 31, 2026, the closing price of Ternium’s ADSs as quoted on the New York Stock Exchange was $40.15 per ADS, giving Tenaris’s ownership stake a market value of approximately $922.3 million. As of that date, the carrying value of Tenaris’s ownership stake in Ternium, based on Ternium’s Consolidated Condensed Interim Financial Statements, was approximately $1,404.7 million.

The Company reviews its participation in Ternium whenever events or circumstances indicate that the asset’s carrying amount may not be recoverable. As of March 31, 2026, the Company concluded that the carrying amount of its investment in Ternium did not exceed its recoverable value.

Usinas Siderúrgicas de Minas Gerais (“Usiminas”) is a Brazilian producer of high-quality flat steel products used in the energy, automotive and other industries.

As of March 31, 2026, the closing price of the Usiminas’ ordinary and preferred shares, as quoted on the B3 - Brasil Bolsa Balcão S.A., was BRL6.66 ($1.28) and BRL6.74 ($1.29), respectively, giving Tenaris’s ownership stake a market value of approximately $62.3 million. As of that date, the carrying value of Tenaris’s ownership stake in Usiminas was approximately $114.3 million.

The Company reviews its participation in Usiminas whenever events or circumstances indicate that the asset’s carrying amount may not be recoverable. As of March 31, 2026, the Company concluded that the carrying amount of its investment in Usiminas did not exceed its recoverable value.

Techgen S.A. de C.V. (“Techgen”) is a Mexican company that operates a natural gas-fired combined cycle electric power plant in the Pesquería area of the State of Nuevo León, Mexico, with a power capacity of 900 MW. As of March 31, 2026, Tenaris held 22% of Techgen’s share capital, and its affiliates, Ternium and Tecpetrol Internacional S.L. (a wholly-owned subsidiary of San Faustin S.A. (“San Faustin”), the controlling shareholder of both Tenaris and Ternium), beneficially owned 48% and 30%, respectively. As of March 31, 2026, the carrying value of Tenaris’s ownership stake in Techgen was approximately $76.6 million.

Techgen entered into certain transportation capacity agreements and an agreement for the purchase of clean energy certificates. As of March 31, 2026, Tenaris’s exposure under these agreements amounted to $32.4 million and $16.0 million, respectively.

In the three-month period ended March 31, 2026, Techgen fully paid the subordinated loans to its sponsors and the guarantees securing the loan were released.

Consolidated Condensed Interim Financial Statements For the three-month period ended March 31, 2026 - all amounts in thousands of U.S. dollars, unless otherwise stated

Tenaris is from time to time subject to various claims, lawsuits and other legal proceedings, including customer, employee, tax and environmental-related claims, in which third parties are seeking payment for alleged damages, reimbursement for losses, or indemnity. Management, with the assistance of legal counsel, periodically reviews the status of each significant matter and assesses potential financial exposure.

Some of these claims, lawsuits and other legal proceedings involve highly complex issues, and often these issues are subject to substantial uncertainties and, therefore, the probability of loss and an estimation of damages are difficult to ascertain. Accordingly, with respect to a large portion of such claims, lawsuits and other legal proceedings, the Company is unable to make a reliable estimate of the expected financial effect that will result from ultimate resolution of the proceeding. In those cases, the Company has not accrued any provision for the potential outcome of these cases.

If a potential loss from a claim, lawsuit or other proceeding is considered probable and the amount can be reasonably estimated, a provision is recorded. Accruals for loss contingencies reflect a reasonable estimate of the losses to be incurred based on information available to management as of the date of preparation of the financial statements and take into consideration litigation and settlement strategies. In a limited number of ongoing cases, the Company was able to make a reliable estimate of the expected loss or range of probable loss and, depending on the likelihood of occurrence, in some of such cases has accrued a provision for such loss but believes that publication of this information on a case-by-case basis would seriously prejudice Tenaris’s position in the ongoing legal proceedings or in any related settlement discussions. Accordingly, in these cases, the Company has disclosed information with respect to the nature of the contingency but has not disclosed its estimate of the range of potential loss.

The Company believes that the aggregate provisions recorded for potential losses in these Consolidated Condensed Interim Financial Statements are adequate based upon currently available information. However, if management’s estimates prove incorrect, current reserves could be inadequate and the Company could incur a charge to earnings which could have a material adverse effect on its results of operations, financial condition, net worth and cash flows.

Below is a summary description of Tenaris’s material legal proceedings which are outstanding as of the date of these Consolidated Condensed Interim Financial Statements. In addition, Tenaris is subject to other legal proceedings, none of which is believed to be material.

The Company is a party to a longstanding lawsuit filed in Brazil by Companhia Siderúrgica Nacional (“CSN”), and various entities affiliated with CSN against the Company’s Brazilian subsidiary Confab and three subsidiaries of Ternium, all of which compose the T/T Group under the Usiminas shareholders agreement. The entities named in the CSN lawsuit had acquired participations in Usiminas in January 2012. The CSN lawsuit alleges that, under applicable Brazilian laws and rules, the acquirers were required to launch a tag-along tender offer to all non-controlling holders of Usiminas ordinary shares for a price per share equal to 80% of the price per share paid in such acquisition, or BRL28.8, and sought an order to compel the acquirers to launch an offer at that price plus interest. If so ordered, the offer would need to be made to 182,609,851 ordinary shares of Usiminas not belonging to Usiminas’ control group. Confab’s share in the offer would be 17.9%.

On September 23, 2013, the first instance court dismissed the CSN lawsuit, and on February 8, 2017, the court of appeals maintained the understanding of the first instance court. On August 18, 2017, CSN filed an appeal to the Superior Court of Justice (“SCJ”) seeking the review and reversal of the decision issued by the Court of Appeals. On September 10, 2019, the SCJ declared CSN’s appeal admissible. On March 7, 2023, the SCJ, by majority vote, rejected CSN’s appeal.

CSN made several submissions in connection with the SCJ March 7, 2023 decision, including a motion for clarification that challenged the merits of the SCJ decision. Decisions at the SCJ are adopted by majority vote. At an October 17, 2023 session, two justices of the SCJ voted in favor of remanding the case to the first instance for it to be retried following production and assessment of the new evidence, and two justices of the SCJ voted, without requiring any further evidence, in favor of granting CSN’s motion for clarification and reversing the March 7, 2023 decision that rejected CSN’s appeal; because the fifth member of SCJ excused himself from voting, a justice from another panel at the SCJ was summoned to produce the tie-breaking vote. On June 18, 2024, the SCJ completed its voting on CSN’s motion for clarification and reversed, by majority vote, its March 7, 2023 decision, and resolved that Confab and the three subsidiaries of Ternium should pay CSN an indemnification in connection with the acquisition by the T/T Group of a participation in Usiminas in January 2012, with CSN being allowed to retain ownership of the Usiminas ordinary shares it currently owns.

Consolidated Condensed Interim Financial Statements For the three-month period ended March 31, 2026 - all amounts in thousands of U.S. dollars, unless otherwise stated

On August 1, 2024, Confab and the other T/T Group entities filed a motion for clarification against the SCJ decision and, subsequently, CSN filed its reply. On December 6, 2024, the SCJ rejected this motion for clarification, confirming the obligation of Confab and the other T/T Group entities to pay indemnification in connection with the 2012 acquisition of the participations in Usiminas. Notwithstanding the foregoing, the SCJ unanimously resolved to modify the applicable monetary adjustment mechanism and to cap the applicable attorney’s fees, thereby lowering the aggregate amount that would be payable if CSN ultimately prevails in this claim. Based on such SCJ decision, assuming monetary adjustment through March 31, 2026, and attorney’s fees in the amount of BRL5 million, the revised aggregate amount potentially payable by Confab if CSN finally prevails on its claims, would be of approximately BRL654 million (approximately $125.3 million at the BRL/$ rate as of such date).

The Company continues to believe that all of CSN's claims and allegations are unsupported and without merit, as confirmed by several opinions of Brazilian legal counsel, two decisions issued by the Brazilian securities regulator in February 2012 and December 2016, the first and second instance court decisions and the March 7, 2023 SCJ decision referred to above, and that in connection with the Usiminas acquisition the T/T Group was not required either to launch a tender offer or to pay indemnification to CSN. Accordingly, on February 10, 2025, Confab and the other T/T Group entities filed a request for extraordinary appeal against the SCJ decisions that ordered an indemnification payment, seeking their review and reversal by the Supreme Federal Tribunal. On September 10, 2025, the Vice-President of the SCJ, without examining the merits, denied leave to proceed with the extraordinary appeal as to certain arguments and ruled it inadmissible as to certain others, and on October 2, 2025, Confab and the other T/T Group entities filed an internal appeal for the special court of the SCJ to reconsider the denial of leave to proceed and a concurrent appeal against the inadmissibility ruling for the Supreme Federal Tribunal to consider admissibility of the extraordinary appeal directly. On November 26, 2025, the special court of the SCJ rejected Confab and the other T/T Group entities' internal appeal. The Supreme Federal Tribunal has not yet ruled on the admissibility of the extraordinary appeal. The Company cannot predict the ultimate resolution on the matter.

On September 21, 2007, an accident occurred in the premises of Veracel Celulose S.A. (“Veracel”) in connection with a rupture in one of the tanks used in an evaporation system manufactured by Confab. The Veracel accident allegedly resulted in material damages to Veracel. Itaú Seguros S.A. (“Itaú”), Veracel’s insurer at the time of the Veracel accident and then replaced by Chubb Seguros Brasil S/A (“Chubb”), initiated a lawsuit against Confab seeking reimbursement of damages paid to Veracel in connection with the Veracel accident. Veracel initiated a second lawsuit against Confab seeking reimbursement of the amount paid as insurance deductible with respect to the Veracel accident and other amounts not covered by insurance. Itaú and Veracel claimed that the Veracel accident was caused by failures and defects attributable to the evaporation system manufactured by Confab. Confab believes that the Veracel accident was caused by the improper handling by Veracel’s personnel of the equipment supplied by Confab in violation of Confab’s instructions. The two lawsuits were consolidated and are considered by the 6th Civil Court of São Caetano do Sul. However, each lawsuit will be adjudicated separately.

On September 28, 2018, Confab and Chubb entered into a settlement agreement pursuant to which on October 9, 2018, Confab paid an amount of approximately $3.5 million to Chubb, without assuming any liability for the accident or the claim.

On October 10, 2018, Confab was notified that the court had issued rulings for both lawsuits. Both decisions were unfavorable to Confab:

Consolidated Condensed Interim Financial Statements For the three-month period ended March 31, 2026 - all amounts in thousands of U.S. dollars, unless otherwise stated

Upon learning of certain government investigations as to whether certain payments were made prior to 2014 from accounts of entities presumably associated with affiliates of the Company to accounts allegedly linked to individuals related to Petróleo Brasileiro S.A. (“Petrobras”) and whether any such payments were intended to benefit the Company’s Brazilian subsidiary Confab, the Audit Committee of the Company's Board of Directors engaged external counsel in connection with the Company’s review of these matters. In addition, the Company voluntarily notified the U.S. Securities and Exchange Commission (“SEC”) and the U.S. Department of Justice (“DOJ”) in October 2016, conducted, with the assistance of external counsel, an internal investigation, and found no evidence corroborating any involvement by the Company or its directors, officers or employees in respect of improper payments. An internal investigation commissioned by Petrobras also found no evidence that Confab obtained any unfair commercial benefit or advantage from Petrobras in return for payments, including improperly obtained contracts. On June 2, 2022, the Company resolved the investigation by the SEC, and the DOJ informed that it had closed its parallel inquiry without taking action. Under the settlement with the SEC, the Company neither admits nor denies the SEC’s findings and on June 24, 2022, paid $53.1 million in disgorgement and prejudgment interest and $25 million for a civil penalty to conclude the matter.

In July 2019, the Company learned that the public prosecutors’ office of Milan, Italy, had completed a preliminary investigation into the same alleged payments and had included in the investigation, among other persons, the Company’s Chairman and Chief Executive Officer, two other board members, Gianfelice Rocca and Roberto Bonatti, and the Company’s controlling shareholder, San Faustin. The Company was not a party to the proceedings. On March 22, 2022, upon completion of the evidentiary phase of the trial, the acting prosecutor requested the first-instance court in Milan in charge of the case to impose sanctions on the Company’s Chairman and Chief Executive Officer, on the other two board members, and on San Faustin. On May 26, 2022, the first-instance court dismissed the case brought by the public prosecutor against the defendants for lack of jurisdiction and stated that the criminal proceeding should not have been initiated. On February 22, 2024, the court of appeals referred the case to the court of cassation, which, on May 23, 2024, confirmed the decision of the first-instance court and closed the case.

In June 2020, the Brazilian public prosecutors’ office requested the indictment of several individuals, including three executives or former executives of Confab and a former agent of Confab, charging them with the alleged crimes of corruption in relation to contracts executed between 2007 and 2010, and money laundering in relation to payments between 2009 and 2013. On December 11, 2024, the Confab executives were acquitted. The acquittal has already been appealed, so the criminal proceedings continue to be underway. Neither the Company nor Confab is a party to these criminal proceedings.

In addition, Petrobras and the Brazilian public prosecutors filed civil claims for alleged damages arising from the same event against, among others, Confab and the Confab executives named in the criminal proceedings referred to above.

The plaintiffs also seek that Confab be prohibited from contracting with, or receiving benefits or exemptions from, the Brazilian state for an unspecified term. Confab became aware of these civil claims in September 2022 and filed its defence in February 2025, among other things, requesting the suspension of the case until a final decision is made on the jurisdiction and the dismissal on the merits of the claims made by Petrobras and the public prosecutors. As of March 31, 2026, the aggregate amount of these claims was estimated at BRL204.7 million (or approximately $39.2 million). Confab believes these claims do not address either the defence arguments or the evidence available to the plaintiffs in Brazil and presented in other jurisdictions and is vigorously contesting them. Based on the advice of legal counsel, the Company cannot predict the outcome of these civil proceedings at this stage.

In late March 2024, the Company became aware of a resolution of Brazil’s General Controllers Office (“Controladoria-Geral da União”, or GCO), which opened administrative responsibility proceedings against Confab and other non-Tenaris affiliates and formed an investigative commission charged with investigating purported irregularities. Potential outcomes of an adverse GCO decision include a declaration of ineligibility for contracting with the Brazilian state for up to six years. Confab received notice in February 2025 and believes that the GCO’s allegations do not address either the defence arguments or the evidence available to the plaintiffs in Brazil and presented in other jurisdictions. On April 7, 2025, Confab filed its defence and contested the allegations. On September 12, 2025, Confab opened discussions with GCO towards seeking a resolution of the matter, and such discussions are ongoing. Based on the advice of legal counsel, the Company cannot predict the outcome of these administrative proceedings at this stage.

Consolidated Condensed Interim Financial Statements For the three-month period ended March 31, 2026 - all amounts in thousands of U.S. dollars, unless otherwise stated

Tenaris Coiled Tubes, LLC (“TCT”), a U.S. subsidiary of the Company, was sued in 2017 by its competitor Global Tubing, alleging defamatory conduct by TCT and seeking a declaration that certain Global Tubing products do not infringe patents held by TCT. TCT counterclaimed that certain Global Tubing products did infringe patents held by TCT, and Global Tubing has since sought to invalidate such patents. On December 13, 2019, Global Tubing filed an amended complaint (including the Company as defendant), alleging, among other things, that TCT and the Company had misled the patent office. On March 20, 2023, the judge granted summary judgment in favor of Global Tubing, concluding that the patents at issue are unenforceable due to inequitable conduct during the patent prosecution process. TCT appealed this judgment, and Global Tubing appealed a previous ruling of the judge. Global Tubing also filed a brief seeking to recover attorneys’ fees, without specifying the amount of those fees. On February 26, 2026, the Federal Circuit issued an opinion reversing the finding of inequitable conduct by TCT, and reversing the lower court’s dismissal of Global Tubing’s antitrust claim.  As a practical matter, both issues will return to the lower court to eventually be resolved in a jury trial. Although it is not possible to predict the final outcome of this matter, the Company believes that any potential losses arising from this case will not be material.

On October 26, 2021, the U.S. Department of Commerce (“DOC”) initiated antidumping duty investigations of oil country tubular goods (“OCTG”) from Argentina, Mexico, and Russia. After the DOC issued affirmative preliminary and final antidumping determinations with respect to imports from Argentina, Mexico and Russia on November 14, 2022, the International Trade Commission determined that the imports under investigation caused injury to the U.S. OCTG industry. Tenaris and other parties appealed the agency determinations from the investigation to the Court of International Trade, and, with respect to certain claims, to the Court of Appeals for the Federal Circuit. In addition, in response to a request from the Government of Argentina, the World Trade Organization (“WTO”) established a panel of experts to consider whether the DOC’s antidumping order applicable to Argentina is consistent with the international obligations of the United States.

As a result of the investigations, Tenaris was required to pay antidumping duty deposits (at a rate of 78.30% for imports from Argentina and 44.93% for imports from Mexico) until such time the imports were reviewed by the DOC to determine whether final duties were necessary for the specific period under review. Tenaris paid such deposits for the first review period (which ran from May 11, 2022, through October 31, 2023) and for subsequent review periods until the final determinations by the DOC discussed below were published. The amount of such deposits was reflected in Tenaris’s costs.

On June 6, 2025, the DOC issued a final determination with respect to imports from Argentina that occurred during the first review period, announcing a final antidumping duty rate of 6.76% for imports by Tenaris. This lower rate (reduced from 78.30%) became the deposit rate for Tenaris’s imports from Argentina as from June 12, 2025. No appeal was filed against the DOC’s final determination and, accordingly, the DOC instructed the customs authorities to liquidate the corresponding refunds at the assessment rate of Tenaris’s imports from Argentina for the first review period, with such instructions becoming effective on August 4, 2025. The resulting expected gain (including interest) up to end of 2025 was recognized in the Consolidated Financial Statements for the year ended December 31, 2025. During March 2026, Tenaris collected these refunds. While the second review period (which ran from November 1, 2023, through October 31, 2024) was rescinded, the DOC has initiated its review of the third review period (which ran from November 1, 2024, through October 31, 2025) for imports from Argentina.

On September 5, 2025, the DOC issued its final determination for imports from Mexico that occurred during the first review period, announcing a final rate of 26.10%. This lower rate (reduced from 44.93%) became the deposit rate for Tenaris’s imports from Mexico as from September 15, 2025. Both petitioners and Tenaris appealed this determination. As a result, the DOC has not instructed the customs authorities to liquidate these entries and will not do so while the appeals are ongoing. The DOC’s preliminary and final determinations for the second review period for imports from Mexico remain pending, and the DOC has initiated its review of the third review period for imports from Mexico.

As a result of these periodic reviews, the deposit rates on future imports can change, and the antidumping duty deposits paid on imports during the relevant review period may be either returned to Tenaris (in whole or in part) or increased.

Consolidated Condensed Interim Financial Statements For the three-month period ended March 31, 2026 - all amounts in thousands of U.S. dollars, unless otherwise stated

In an audit report issued by an audit team of the U.S. Customs and Border Protection (“CBP”), CBP concluded that Tenaris should have paid antidumping duties on imports of mechanical and other pipe, which CBP believes to be subject to the antidumping orders on OCTG from Argentina and Mexico. CBP’s audit report calculated loss of revenue to the United States of approximately $49.6 million for years 2022, 2023 and 2024. However, CBP also appears to indicate that its calculation will be adjusted to conform with any clarification of the scope of the relevant OCTG orders that the DOC may issue. Tenaris considers imports of mechanical or other pipe to be out of scope of the OCTG orders and has filed a scope clarification request with the DOC. Based on the advice of counsel, Tenaris believes that the loss contingency arising from the CBP report is neither probable nor capable of a reliable estimate at this time and, accordingly, no provision has been made with respect to such 2022, 2023 and 2024 imports.

CBP separately instructed Tenaris to modify its treatment of imports effective January 2025 and forward so that imports of certain mechanical and other pipe would be considered to be subject to the antidumping orders on OCTG from Argentina and Mexico. As a result, unless CBP changes its stated position on its own initiative or after clarification by DOC, the entries on and after January 1, 2025, will require the payment of antidumping duty deposits, and the liquidation of these entries will remain suspended during the antidumping administrative review process. The amount of such deposits is reflected in Tenaris’s costs.

On April 21, 2026, the Canadian International Trade Tribunal (“CITT”) issued its findings in an inquiry concerning OCTG. Following a final determination of dumping issued by the President of the Canada Border Services Agency on March 23, 2026, the CITT found that, pursuant to the Special Import Measures Act, the dumping of OCTG originating in several countries, including Mexico, and of OCTG produced or exported by, or on behalf of, Tenaris (or its affiliates) from the United States, has caused injury to the domestic industry in Canada. Seamless OCTG originating in the United States and exported or produced by or on behalf of Tenaris is excluded from the scope of the findings. The CITT further found that the circumstances relating to massive importation are not present. As a result of these findings, antidumping duties will apply to imports of the subject goods into Canada at prices below the normal values determined for each type of products. The Company is assessing the implications of the findings on its OCTG sales into Canada.

Set forth is a description of Tenaris’s main outstanding commitments:

Consolidated Condensed Interim Financial Statements For the three-month period ended March 31, 2026 - all amounts in thousands of U.S. dollars, unless otherwise stated