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, 2021

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)

Indicate by check mark whether the registrant files or will file annual reports under cover of Form 20-F or Form 40-F:

Indicate by check mark if the registrant is submitting the Form 6-K in paper as permitted by Regulation S-T Rule 101(b)(1):

Indicate by check mark if the registrant is submitting the Form 6-K in paper as permitted by Regulation S-T Rule 101(b)(7):

Banco Santander, S.A.

TABLE OF CONTENTS

Item 1

Banco Santander, S.A. (“Banco Santander”), in compliance with the Securities Market legislation, hereby announces:

OTHER RELEVANT INFORMATION

Banco Santander hereby announces that today, following a revision to its methodologies for rating banks and non-bank financial institutions, S&P Global Ratings has taken the following rating actions on Banco Santander:

Boadilla del Monte (Madrid), 16 December 2021

No offer

The information contained in this document is subject to, and must be read in conjunction with, all other publicly available information, including, where relevant any fuller disclosure document published by Santander. Any person at any time acquiring securities must do so only on the basis of such person’s own judgment as to the merits or the suitability of the securities for its purpose and only on such information as is contained in such public information having taken all such professional or other advice as it considers necessary or appropriate in the circumstances and not in reliance on the information contained in this document. No investment activity should be undertaken on the basis of the information contained in this document. In making this document available Santander gives no advice and makes no recommendation to buy, sell or otherwise deal in shares in Santander or in any other securities or investments whatsoever.

Neither this document nor any of the information contained therein constitutes an offer to sell or the solicitation of an offer to buy any securities. No offering of securities shall be made in the United States except pursuant to registration under the U.S. Securities Act of 1933, as amended, or an exemption therefrom. Nothing contained in this document is intended to constitute an invitation or inducement to engage in investment activity for the purposes of the prohibition on financial promotion in the U.K. Financial Services and Markets Act 2000.

SIGNATURE

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.