6-K

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, DC 20549

_____________

FORM 6-K

Report of Foreign Issuer

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

the Securities and Exchange Act of 1934

For April 22, 2026

Commission file number: 1-13.396

Transportadora de Gas del Sur S.A.

Cecilia Grierson 355, piso 26

(1107), Capital Federal

Argentina

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

Form 20-F  X  Form 40-F

Indicate by check mark if registrant is submitting the Form 6-K in paper as permitted by Regulation S-T Rule 101(b)(1): __

Indicate by check mark if registrant is submitting the Form 6-K in paper as permitted by Regulation S-T Rule 101(b)(7): __

Indicate by check mark whether the registrant by furnishing the information contained in this Form is also thereby furnishing the information to the Commission pursuant to the Rule 12g3-2(b) under the Securities Exchange Act of 1934.

Yes   No X

If "Yes" is marked, indicate below the file number assigned to the registrant in connection with Rule 12g3-2(b):

City of Buenos Aires, April 22, 2026.

E-NOTA-20260422-62126

Messrs.

Comisión Nacional de Valores (Argentine Securities and Exchange Commission)

Bolsas y Mercados Argentinos S.A. (Argentine Stock Exchanges and Markets)

Bolsa de Comercio de Buenos Aires (Buenos Aires Stock Exchange)

Gerencia Técnica y de Valores Negociables (Technical and Negotiable Securities Management)

A3 Mercados S.A. (A3 Markets)

Re: Material Fact. Regular Transaction with Related Parties. Section 72 Act no. 26,831.

Dear Sirs,

I am writing to you in my capacity as Head of Market Relations of Transportadora de Gas del Sur S.A. (“tgs” or the “Company”), in order to report that in its meeting held today, the Board of Directors approved the gas reference prices for Spot purchases for Plant Thermal Reduction with Related Parties for the 2026 winter period (the “Reference Prices”).

Prior to approval of the Reference Prices, tgs Audit Committee was asked to issue a report in compliance with section 72 of Capital Markets Act no. 26,831.

On April 22, 2026, the Audit Committee concluded and informed the Board of Directors that the transactions with Related Parties carried out pursuant to and under the terms of the Reference Prices can be deemed to be reasonably entered into on an arm’s length basis.

The Audit Committee’s reports are available for consultation by accredited shareholders if so desired, upon request via email at: [email protected].

Yours sincerely

Hernán Diego Flores Gómez

Head of Market Relations

SIGNATURES

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.

Transportadora de Gas del Sur S.A.

Date: April 22, 2026.