Company: BCDRF
Filing Date: 2025-08-29
Form Type: 6-K
Source: 0000950103-25-010950
Chunk: 1

Company: Banco Santander, S.A.
Filing Date: 2025-08-29
Form: 6-K
Chunk 1
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 September 
 2030; and                                                                  |

| - | the interest                                                                              
 rate (previously being Compounded SOFR 6 months plus 53.826 basis points) applicable from 
 the next interest payment date (excluded), i.e., 4th September 2025, to the new           
 maturity date is: Compounded SOFR 6 months plus 55.942 basis points.                      |

In everything not expressly described in the preceding paragraphs, the same terms and conditions that were established in the Final Conditions, prior to this modification, will still apply.

New Final Conditions applicable to Series 4 can be found on the CNMV website.

Likewise, it is hereby stated that all the necessary communications have been made to the relevant bodies.

The foregoing is hereby disclosed as other relevant information for all relevant purposes.

Boadilla del Monte (Madrid), 29 August 2025

<div align='center'>IMPORTANT INFORMATION</div>

Not a securities offer

This document
and the information it contains does not constitute an offer to sell nor the solicitation of an offer to buy any securities.

<div align='center'>SIGNATURE</div>

Pursuant to the requirements of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned, thereunto duly authorized.

| Date: | August 29, 2025 |     | Banco Santander, S.A. 
 By:                   | /s/ Pedro de Mingo Kaminouchi |                              |
|:------|:----------------|:----|:----------------------|:------------------------------|:-----------------------------|
|       |                 |     |                       | Name:                         | Pedro de Mingo Kaminouchi    |
|       |                 |     |                       | Title:                        | Head of Corporate Compliance |