Company: BCDRF
Filing Date: 2025-05-07
Form Type: 6-K
Source: 0000950103-25-005801
Chunk: 0

Company: Banco Santander, S.A.
Filing Date: 2025-05-07
Form: 6-K
Chunk 0
---
<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 May, 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. (“Banco Santander”),
in compliance with the Securities Market legislation, hereby announces:

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

The Bank of Spain has formally notified the new
binding minimum requirement for own funds and eligible liabilities (“MREL”), both total and subordinated, for the
resolution group headed by Banco Santander (the “Resolution Group”), which has been determined by the
Single Resolution Board (“SRB”) and is applicable upon receipt of the notification. This notification (the “current notification”) replaces and supersedes the previously applicable notification which was announced as other relevant information
on 24 June 2024 (CNMV registration number 29289) (the “former notification”).

The MREL requirement (“Total MREL”)
is expressed as a percentage of the Resolution Group’s total risk-weighted assets (Total Risk Exposure Amount, “TREA”)
and of leverage exposure (Leverage Ratio Exposure, “LRE”) as of 31 December 2023. Within this Total MREL, a requirement
which must be met through own funds and subordinated eligible liabilities (“Subordinated MREL”) has been determined.

In accordance with the current notification, the
Resolution Group must comply with the following MREL requirements:

The Total MREL requirement and the Subordinated
MREL requirement in terms of TREA do not include the applicable Combined Buffer Requirement. The estimated Combined Buffer Requirement,
applicable on the TREA in accordance with the applicable regulation and the supervisory criteria