Company: BCDRF
Filing Date: 2025-08-29
Form Type: 6-K
Source: 0000950103-25-010950
Chunk: 0

Company: Banco Santander, S.A.
Filing Date: 2025-08-29
Form: 6-K
Chunk 0
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<div align='center'>FORM 6-K

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

Report of Foreign Issuer

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

the Securities Exchange Act of 1934

For the month of August, 2025

Commission File Number: 001-12518

Banco Santander, S.A.

(Exact name of registrant as specified in its charter)

Ciudad Grupo Santander

28660 Boadilla del Monte (Madrid) Spain

(Address of principal executive office)</div>

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 |

<div align='center'>Banco Santander, S.A.

TABLE OF CONTENTS</div>

Item 1

Banco Santander, S.A. (the “Issuer ” or the “Bank ”), in compliance with the Securities Market legislation, hereby communicates the following:

<div align='center'>OTHER RELEVANT INFORMATION</div>

In relation to the “Issuance of Banco Santander, S.A. Internationalization Covered Bonds Series 4 – March 2026 ” (“ Emisión de Cédulas de Internacionalización Banco Santander, S.A. Serie 4 – Marzo 2026”), with ISIN code ES0413900707, for an amount of one billion dolars (USD 1,000,000,000), whose Final Conditions were filed with the Spanish National Securities Market Commission (the “CNMV ”) on 4 March 2021 (hereinafter, as amended on the 3 rdMay 2023, the “Issuance” or the “Series 4 ”)”, the Issuer has carried out a process to gather the consent of each and every investor of the Issuance for the purpose of: (i) extending the maturity of the Issuance, and accordingly, (ii) modifying the applicable interest rate which should be applicable from the next interest payment date (excluded) to the new maturity date (included).

In particular, once the consent of the holders representing 100% of the Issuance has been obtained, the following modifications have been made:

| - | the maturity                                                               
 date (previously being 4th March 2026) is extended up to the 4th