Filed Pursuant to Rule 424(b)(5)
Registration Statement No. 333-271955
The information in this preliminary prospectus supplement is not
complete and may be changed. This preliminary prospectus supplement and the accompanying prospectus are not an offer to sell these securities nor do they seek an offer to buy these securities in any jurisdiction where the offer or sale is not
permitted.
Subject to Completion
Preliminary Prospectus Supplement dated October 30, 2023
PRELIMINARY PROSPECTUS SUPPLEMENT
(to prospectus dated
May 16, 2023)
$
Banco Santander, S.A.
$ Senior Preferred Callable Floating Rate Notes due 2027
$ % Senior Preferred Callable
Fixed-to-Fixed Rate Notes due 2027
$ % Senior Preferred Fixed Rate Notes due 2028
$ % Senior Preferred Fixed Rate Notes due 2033
We are offering $ principal amount of Senior Preferred Callable Floating Rate Notes due 2027 (the SP 2027 Floating
Rate Notes), $ principal amount of % Senior Preferred Callable Fixed-to-Fixed Rate Notes due 2027 (the SP 2027 Fixed-to-Fixed Rate Notes), $ principal amount of % Senior Preferred Fixed Rate Notes due 2028 (the SP 2028 Fixed Rate
Notes) and $ principal amount of % Senior Preferred Fixed Rate Notes due 2033 (the SP 2033 Fixed Rate Notes, and together with the SP 2027 Floating Rate Notes, the SP 2027 Fixed-to-Fixed Rate Notes and the SP 2028 Fixed Rate Notes, the Notes).
The SP 2027 Floating Rate Notes will bear interest at the Floating Rate Interest Rate (as defined herein). From and including the date of
issuance, interest will be payable quarterly in arrears on the SP 2027 Floating Rate Notes on February , May , August , and November of each
year, beginning on February , 2024. Unless we redeem the SP 2027 Floating Rate Notes earlier, the SP 2027 Floating Rate Notes will be due on November , 2027.
The SP 2027 Fixed-to-Fixed Rate Notes will bear interest at
(i) a fixed rate of % per annum in respect of the period from (and including) the date of issuance to (but excluding) November , 2026 (the Reset Date) and (ii) a fixed rate equal to the
applicable U.S. Treasury Rate as of the Reset Determination Date (as such terms are defined herein) plus % per annum in respect of the period from (and including) the Reset Date to (but excluding) November ,
2027. From and including the date of issuance, interest will be payable semi-annually in arrears on the SP 2027 Fixed-to-Fixed Rate Notes on
May and November of each year, beginning on May , 2024. Unless we redeem the SP 2027
Fixed-to-Fixed Rate Notes earlier, the SP 2027 Fixed-to-Fixed Rate Notes will be due on
November , 2027.
The SP 2028 Fixed Rate Notes will bear interest at a rate of % per year. From and
including the date of issuance, interest will be payable semi-annually in arrears on the SP 2028 Fixed Rate Notes on May and November of each year, beginning on May ,
2024. The SP 2028 Fixed Rate Notes will be due on November , 2028.
The SP 2033 Fixed Rate Notes will bear
interest at a rate of % per year. From and including the date of issuance, interest will be payable semi-annually in arrears on the SP 2033 Fixed Rate Notes on May and November of
each year, beginning on May , 2024. The SP 2033 Fixed Rate Notes will be due on November , 2033.
The Notes will be issued in minimum denominations of $200,000 and integral multiples of $200,000 in excess thereof.
The payment obligations of Banco Santander, S.A. (Banco Santander) in respect of principal under the Notes constitute direct,
unconditional, unsubordinated and unsecured obligations (créditos ordinarios) of Banco Santander and, in accordance with Additional Provision 14.2 of Law 11/2015 (as defined herein) (but subject to any other ranking that may apply as a
result of any mandatory provision of law (or otherwise)), upon the insolvency of Banco Santander, such payment obligations rank (i) pari passu among themselves and with any other Senior Higher Priority Liabilities (as defined herein) and
(ii) senior to (x) any Senior Non Preferred Liabilities (as defined herein) and (y) any present and future subordinated obligations (créditos subordinados) of Banco Santander in accordance with Article 281 of the Spanish
Insolvency Law (as defined herein).
By its acquisition of the Notes, each holder (which, for the purposes of this clause, includes each
holder of a beneficial interest in the Notes) acknowledges, accepts, consents to and agrees to be bound by the terms of the Notes related to the exercise of the Bail-in Power (as defined herein) set forth
under Description of Debt SecuritiesAgreement and Acknowledgement with Respect to the Exercise of the Bail-in Power in the accompanying prospectus. See
Notice to Investors on page S-i of this prospectus supplement for further information.
The Notes are not deposits or savings accounts and are not insured by the Federal Deposit Insurance Corporation or any other governmental agency
of the Kingdom of Spain, the United States or any other jurisdiction.
We may redeem any or both of the SP 2028 Fixed Rate Notes and the SP
2033 Fixed Rate Notes, in whole but not in part, respectively, at 100% of their principal amount plus accrued and unpaid interest (if any) at any time upon the occurrence of certain tax events. We may redeem any or both of the SP 2027 Floating Rate
Notes and the SP 2027 Fixed-to-Fixed Rate Notes, in whole but not in part, respectively, at 100% of their principal amount plus accrued and unpaid interest (if
any) (i) on the Optional Redemption Date, or (ii) at any time upon the occurrence of certain tax events. We may not redeem the Notes under other circumstances, and there are no put rights with respect to the Notes.
We intend to apply to list the Notes on the New York Stock Exchange in accordance with its rules.
Investing in the Notes involves risks. See Risk Factors beginning on page S-14 of this prospectus supplement, page 7 of the accompanying prospectus as well as those discussed under the heading Risk Factors in the Groups Annual Report on Form 20-F for the year ended December 31, 2022 and under the heading Part 3. Supplemental InformationItem 4. Risk Factors in the Groups Report on Form 6-K
filed with the SEC on July 28, 2023 (Accession No. 0000891478-23-000109), which are incorporated by reference herein.