Company: BCDRF
Filing Date: 2025-10-31
Form Type: 424B5
Source: 0001193125-25-260533
Chunk: 35

Company: Banco Santander, S.A.
Filing Date: 2025-10-31
Form: 424B5
Chunk 35
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 footnote to the New York Federal Reserve’s
publication would indicate the revision. This revision threshold will be reviewed periodically by the New York Federal Reserve and may be changed based on market conditions.

As the Secured Overnight Financing Rate is published by the New York Federal Reserve based on data received from other sources, we have no
control over its determination, calculation or publication. There can be no guarantee that the Secured Overnight Financing Rate will not be discontinued or fundamentally altered in a manner that is materially adverse to the interests of investors in
the 2030 Floating Rate Notes. The interest rate for any Interest Period will not be adjusted for any modifications or amendments to the SOFR Index or the Secured Overnight Financing Rate data that the New York Federal Reserve may publish after the
interest rate for such Interest Period has been determined. If the manner in which the Secured Overnight Financing Rate is calculated is changed, that change may result in a reduction of the amount of interest payable on the 2030 Floating Rate Notes
and the trading prices of the 2030 Floating Rate Notes.

S-20

CAPITALIZATION OF THE GROUP The following table sets forth the Group’s indebtedness and capitalization as of September 30, 2025, included in the Group’s unaudited condensed consolidated interim financial statements as of September 30, 2025, in accordance with IFRS-IASB on an actual basis and as adjusted to reflect the issuance of the Notes (converting the principal amount of the Notes into euros at the European Central Bank reference rate for euro at September 30, 2025, of $1.1741 per €1.00). This table should be read in conjunction with the Group’s unaudited condensed consolidated interim financial statements as of September 30, 2025, the notes related thereto and the financial and operating data incorporated by reference into this prospectus supplement and the accompanying prospectus.

|                                                     |     | As of September 30,   
 2025                  |         |   |     |             |         |   |
|:----------------------------------------------------|:----|:----------------------|--------:|:--|:----|:------------|--------:|:--|
|                                                     |     | Actual                |         |   |     | As          
 Adjusted(1) |         |   |
|                                                     |     | -in millions of euros |         |   |     |             |         |   |
| Outstanding indebtedness                            |     |                       |         |   |