Company: BCDRF
Filing Date: 2025-06-10
Form Type: 6-K
Source: 0000950103-25-007199
Chunk: 0

Company: Banco Santander, S.A.
Filing Date: 2025-06-10
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 June, 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-  |

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

TABLE OF CONTENTS</div>

Item 1

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

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

| Further                                                                                                                                      
 to the notice of other relevant information registered with the Spanish National Securities Market Commission (Comisión                      
 Nacional del Mercado de Valores) on 3 June 2025 (registry number 35106), it is communicated that on 6 June 2025 the public                   
 deed of capital reduction (and consequent Bylaw amendment) for the amount of EUR 133,583,475, through the cancellation of 267,166,950 own    
 shares, representing approximately 1.76% of the Bank’s share capital, was registered with the Commercial Registry of Santander.              
 Consequently,                                                                                                                                
 the Bank’s share capital has been set at EUR 7,442,662,686, represented by 14,885,325,372 shares with a nominal value                        
 of EUR 0.50 each. All of the shares belong to the same class and have the same rights.                                                       
 It                                                                                                                                           
 is stated for the record that, once the eight buyback programmes carried out against results since 2021 have been completed, the             
 accumulated share capital reduction amounts to EUR 1,227,657,965, with the Bank having repurchased 2,455,315,930 shares since November 2021, 
 approximately 14.16 % of its outstanding shares as of that date