Company: BCDRF
Filing Date: 2025-06-24
Form Type: 6-K
Source: 0000950103-25-007750
Chunk: 0

Company: Banco Santander, S.A.
Filing Date: 2025-06-24
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-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 our notice of inside information
on 24 June 2025 (registered under number 2784) announcing 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") and the intention to issue a new series of contingent convertible perpetual
preferred securities (the “New Preferred Securities”), Santander announces today that it has set (i) the final terms
and conditions of the New Preferred Securities, which aggregate nominal amount will amount to €1,500,000,000, and (ii) the Maximum
Acceptance Amount in respect of the Offer in €1,500,000,000 in aggregate nominal amount of Preferred Securities.

The remuneration of the New Preferred
Securities, the payment of which is subject to certain conditions and is also discretionary, has been set at 6.00 per cent. on an annual
basis for the first six years (2 July 2031), and it will be