Company: BCDRF
Filing Date: 2025-07-01
Form Type: 6-K
Source: 0000950103-25-008222
Chunk: 0

Company: Banco Santander, S.A.
Filing Date: 2025-07-01
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 July, 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., (“ Santander” or the “ Offeror”) in accordance with the provisions of the securities market legislation, communicates the following:

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

Further to the communications made on
24 June 2025 (registered under numbers 2784 and 35457) regarding the invitation by Santander to holders of its outstanding €1,500,000,000
4.375 per cent. Non-Step-Up Non-Cumulative Contingent Convertible Perpetual Preferred Tier 1 Securities (ISIN: XS2102912966) (the “Preferred Securities”) to tender their Preferred Securities for purchase by the Offeror for cash in an aggregate nominal amount of up
to the Maximum Acceptance Amount (the “Offer”), the Offeror now announces the results of the Offer.

Capitalised terms used but not otherwise
defined in this announcement shall have the meaning given to them in the Tender Offer Memorandum.

The Expiration Time for the Offers was
5.00 p.m. (CET) on 30 June 2025.

The Offeror hereby announces that it
will accept for purchase in accordance with the terms and subject to the conditions set out in the Tender Offer Memorandum and at the
relevant Purchase Price, all Preferred Securities validly offered for Sale pursuant to the Offer, without pro-ration, in an aggregate
nominal amount of €466,600,000 (the Acceptance Amount), as set out in the table below.

| Description of