YPF Sociedad Anonima

REPORT OF FOREIGN PRIVATE ISSUER PURSUANT TO RULE 13A-16 OR 15D-16 UNDER THE SECURITIES EXCHANGE ACT OF 1934 For the month of September 2026 Commission File Number: 001-12102

YPF Sociedad Anónima (Exact name of registrant as specified in its charter)

Macacha Güemes 515 C1106BKK Buenos Aires, Argentina (Address of principal executive office)

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 ☒ Form 40-F ☐

YPF Sociedad Anónima TABLE OF CONTENT ITEM 1 Translation of letter to the Argentine Securities Commission ( Comisión Nacional de Valores ) dated September 14, 2026.

Buenos Aires, September 14, 2026. COMISIÓN NACIONAL DE VALORES ("CNV") 25 de Mayo 175 Buenos Aires BOLSAS Y MERCADOS ARGENTINOS S.A. ("ByMA") Sarmiento 299 Buenos Aires A3 MERCADOS S.A. ("A3 Mercados") Maipú 1210 Buenos Aires

Ref. : Material Event. Agreement between YPF S.A. and Pluspetrol S.A. - Closing Ladies and Gentlemen, We are writing to you in order to comply with the CNV Rules and the corresponding regulations of ByMA and A3 Mercados. In this regard, and continuing with our communications dated January 22 and April 30 of this year, we hereby inform you that on today's date, September 14, 2026, upon satisfaction of the conditions precedent, the closing of the transaction took place whereby Vaca Muerta Inversiones S.A. ("VMI", a company 100% controlled by YPF) assigned to Pluspetrol S.A. a 20% interest in the Temporary Joint Venture (Unión Transitoria) contracts for the "La Escalonada"and"Rincón La Ceniza" Areas (Province of Neuquén), and the corresponding joint operating agreements (the "Contracts"). As a result of this assignment, VMI's interest in the Contracts will be 25%. Sincerely,

Margarita Chun Market Relations Officer YPF S.A.