Company: BCDRF
Filing Date: 2025-12-02
Form Type: 6-K
Source: 0000950103-25-015596
Chunk: 0

Company: Banco Santander, S.A.
Filing Date: 2025-12-02
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 December, 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” or the “Bank”), in compliance with the Securities Market legislation, hereby announces the following:

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

Banco Santander announces that it has
completed an accelerated placement (the “Placement”) of 3,576,626 ordinary shares of its subsidiary Santander Bank
Polska S.A. (“Santander Bank Polska”), representing c. 3.5% of Santander Bank Polska’s existing share capital,
at a price of PLN 482.0 per ordinary share.

Following the Placement and subsequent
to the completion of the envisaged sale of approximately 49% of Santander Bank Polska to Erste Group Bank AG (“Erste”)
announced on 5 May 2025 by Banco Santander, Banco Santander will hold approximately 9.7% of shares in Santander Bank Polska.

Banco Santander will remain committed
to the Polish market through Santander Consumer and its planned strategic collaboration with Erste which aims to leverage each firm's
respective strengths and footprint in Corporate & Investment Banking (CIB) while allowing Erste access to Santander’s payments
platforms.

The Placement is aligned with Banco
Santander’s strategic focus on proactive capital optimization to create shareholder value.

In relation to the Placement, the remaining
shares in Santander Bank Polska still held by Banco Santander will be subject to a 90-day post-closing lock-up period, subject to