Company: BCDRF
Filing Date: 2025-02-28
Form Type: 20-F
Source: 0000891478-25-000054
Chunk: 0

Company: Banco Santander, S.A.
Filing Date: 2025-02-28
Form: 20-F
Chunk 0
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### SECURITIES AND EXCHANGE COMMISSION

#### Washington, D.C. 20549

#### FORM 20-F
| (Mark One)                                |     |                                                                                                |
| ☐                                         |     | REGISTRATION STATEMENT PURSUANT TO SECTION 12(b) OR (g) OF THE SECURITIES EXCHANGE ACT OF 1934 |
| OR                                        |     |                                                                                                |
| ☒                                         |     | ANNUAL REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934           |
| For the fiscal year ending31 December2024 |     |                                                                                                |
| OR                                        |     |                                                                                                |
| ☐                                         |     | TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934       |

<div align='center'>For the transition period from to</div>

| ☐ |     | SHELL COMPANY REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934 |

#### Date of event requiring this shell company report

#### Commission file number 001-12518

#### BANCO SANTANDER, S.A.
<div align='center'>(Exact name of Registrant as specified in its charter)</div>

#### Kingdom of Spain
<div align='center'>(Jurisdiction of incorporation)</div>

#### Ciudad Grupo Santander

#### 28660 Boadilla del Monte (Madrid), Spain
<div align='center'>(address of principal executive offices)</div>

#### José G. Cantera

#### Banco Santander, S.A.
<div align='center'>Ciudad Grupo Santander- 28660 Boadilla del Monte (Madrid), Spain</div>

#### Tel: +34 91 259 65 20
<div align='center'>(Name, Telephone, E-mail and/or Facsimile number and Address of Company Contact Person)</div>

<div align='center'>Securities registered or to be registered, pursuant to Section 12(b) of the Act</div>

| Title of each class                                                                                                                              |     |                |     | Name of each exchange on which registered |
| American Depositary Shares, each representing the right to receive one Share of Capital Stock of Banco Santander, S.A., par value euro 0.50 each |     | SAN            |     | New York Stock Exchange                   |
| Shares of