Banco Santander SA

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM 20-F

For the transition period from to

Date of event requiring this shell company report

Commission file number 001-12518

(Exact name of Registrant as specified in its charter)

Kingdom of Spain

(Jurisdiction of incorporation)

Ciudad Grupo Santander

28660 Boadilla del Monte (Madrid), Spain

(address of principal executive offices)

José G. Cantera

Banco Santander, S.A.

Ciudad Grupo Santander -28660 Boadilla del Monte Madrid, Spain

Tel: +3491 259 65 20

(Name, Telephone, E-mail and/or Facsimile number and Address of Company Contact Person)

Securities registered or to be registered, pursuant to Section 12(b) of the Act

*Banco Santander Shares are not listed for trading, but are only listed in connection with the registration of the American Depositary Shares, pursuant to requirements of the New York Stock Exchange.

Securities registered or to be registered pursuant to Section 12(g) of the Act: None (Title of Class)

Securities for which there is a reporting obligation pursuant to Section 15(d) of the Act: None (Title of Class)

Indicate the number of outstanding shares of each of the issuer’s classes of capital stock or common stock as of the close of business covered by the annual report 16,184,146,059 shares

Indicate by check mark if the registrant is a well-known seasoned issuer, as defined in Rule 405 of the Securities Act. Yes ☒ No☐

If this report is an annual or transition report, indicate by check mark if the registrant is not required to file reports pursuant to Section 13 or 15(d) of the Securities Exchange Act of 1934. Yes☐ No ☒

Indicate by check mark whether the registrant (1) has filed all reports required to be filed by Section 13 or 15(d) of the Securities Exchange Act of 1934 during the preceding 12 months (or for such shorter period that the registrant was required to file such reports), and (2) has been subject to such filing requirements for the past 90 days. Yes ☒ No☐

Indicate by check mark whether the registrant has submitted electronically every Interactive Data File required to be submitted pursuant to Rule 405 of Regulation S-T during the preceding 12 months (or for such shorter period that the registrant was required to submit such files). Yes ☒ No☐

Indicate by check mark whether the registrant is a large accelerated filer, an accelerated filer, a non-accelerated filer, or an emerging growth company. See definition of “large accelerated filer”, "accelerated filer", and "emerging growth company" in Rule 12b-2 of the Exchange Act. (Check one):

Emerging growth company☐

If an emerging growth company that prepares its financial statements in accordance with U.S. GAAP, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards† provided pursuant to Section 13(a) of the Exchange Act.☐

† The term “new or revised financial accounting standard” refers to any update issued by the Financial Accounting Standards Board to its Accounting Standards Codification after April 5, 2012.

Indicate by check mark whether the registrant has filed a report on and attestation to its management’s assessment of the effectiveness of its internal

control over financial reporting under Section 404(b) of the Sarbanes-Oxley Act (15 U.S.C. 7262(b)) by the registered public accounting firm that prepared or issued its

audit report. Yes☒ No☐

If securities are registered pursuant to Section 12(b) of the Act, indicate by check mark whether the financial statements of the registrant included in the filing reflect the correction of an error to previously issued financial statements.☐

Indicate by check mark whether any of those error corrections are restatements that required a recovery analysis of incentive-based compensation received by any of the registrant’s executive officers during the relevant recovery period pursuant to §240.10D-1(b).☐

Indicate by check mark which basis of accounting the registrant has used to prepare the financial statements included in this filing:

If “Other” has been checked in response to the previous question indicate by check mark which financial statement item the registrant has elected to follow. Item 17☐Item 18☐

If this is an annual report, indicate by check mark whether the registrant is a shell company (as defined in Rule 12b-2 of the Exchange Act). Yes☐No☒

This annual report on Form 20-F for the year ended 31 December 2023, includes two parts: (i) consolidated directors’ report, auditor's report and consolidated financial statements, and (ii) supplemental information. Set forth below is a table listing the required items for Form 20-F and the location where the relevant disclosure in this annual report can be found.

CROSS REFERENCE TO FORM 20-F

TABLE OF CONTENTS

Part 1.

Consolidated directors´ report, auditor's report and consolidated financial statements

Think Value

Think Customer

Think Global

2023 Annual report

santander.com

2023Annual reportUnless otherwise specified, references in this annual report to other documents, including but not limited to other reports and websites, including our own, are for information purposes only. If the contents of such other documents and websites refer to this annual report, they are not nor should be considered part of it.Unless the context suggests otherwise, 'Banco Santander' means Banco Santander, S.A., and 'Santander', 'the Group' and 'Grupo Santander' mean Banco Santander, S.A. and subsidiaries.

Consolidated directors’ report

7 Business model and strategy

8 The Santander Way

9 Our business model

10 2023 results

12 Looking ahead

19 Responsible banking

Consolidated non-financial information statement

23 Responsible banking over view

28 Materiality assessment

30 Supporting the transition

44 Responsible investment

46 Acting responsibly towards employees

55 Acting responsibly towards customers

61 Supporting communities

64 Business conduct

70 Our progress in figures

89 Further information

106 Sustainability reporting standards and references

177 Corporate Governance

180 2023 Overview

186 Ownership structure

192 Shareholdersand general meeting

199 Board of directors

250 Senior management team

182 Remuneration

278 Group structure and internal governance

280 Internal control over financial reporting (ICFR)

287 Other corporate governance information

325 Economic and financial review

328 Economy, regulation and competition

332 Group selected data

334 Group financial performance

377 Financial information by segment

427 Research, development and innovation (R&D&I)

430 Significant events since year end

431 Trend information 2024

441 Alternative performance measures (APMs)

451 Risk, compliance& conduct management

454 Risk, compliance & conduct management

459 Risk management and control model

465 Credit risk

477 Market, structural and liquidity risk

489 Capital risk

491 Operational risk

497 Compliance& conduct risk

503 Model risk

505 Strategic risk

507 ESG risk factors

513 Glossary ofterms, acronyms and abbreviations

Auditor's report and consolidated

financial statements

521 Auditor's report

531 Consolidated financial statements

547 Notes to the consolidated financial statements

785 Appendix