桑坦德银行美股招股说明书(2025-10-31版)

$2,800,000,000 Banco Santander, S.A. $300,000,000 Senior Non Preferred Floating Rate Notes due 2030 $1,250,000,000 4.551% Senior Non Preferred Fixed Rate Notes due 2030$1,250,000,000 5.127% Senior Non Preferred Fixed Rate Notes due 2035 We are offering $300,000,000 principal amount of Senior Non Preferred Floating Rate Notes due 2030 (the “2030 Floating Rate Notes”),$1,250,000,000 principal amount of 4.551% Senior Non Preferred Fixed Rate Notes due 2030 (the “2030 Fixed Rate Notes”), and $1,250,000,000principal amount of 5.127% Senior Non Preferred Fixed Rate Notes due 2035 (the “2035 Fixed Rate Notes” and, together with the 2030 Floating RateNotes and the 2030 Fixed Rate Notes, the “Notes”). The 2030 Floating Rate Notes will bear interest at the 2030 Floating Rate Interest Rate (as defined herein). From and including the date ofissuance, interest will be payable quarterly in arrears on the 2030 Floating Rate Notes on February6, May6, August6 and November6 of each year,beginning on February6, 2026. Unless we redeem the 2030 Floating Rate Notes earlier, the 2030 Floating Rate Notes will be due on November6, 2030. The 2030 Fixed Rate Notes will bear interest at a rate of 4.551% per year. From and including the date of issuance, interest will be payable semi-annually in arrears on the 2030 Fixed Rate Notes on May6 and November6 of each year, beginning on May6, 2026. Unless we redeem the 2030 FixedRate Notes earlier, the 2030 Fixed Rate Notes will be due on November6, 2030. The 2035 Fixed Rate Notes will bear interest at a rate of 5.127% per year. From and including the date of issuance, interest will be payable semi-annually in arrears on the 2035 Fixed Rate Notes on May6 and November6 of each year, beginning on May6, 2026. Unless we redeem the 2035 FixedRate Notes earlier, the 2035 Fixed Rate Notes will be due on November6, 2035. 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 senior non preferred obligations (créditos ordinarios no preferentes) of Banco Santander and, in accordance withAdditional 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 oflaw (or otherwise), upon the insolvency of Banco Santander, such payment obligations rank (i)pari passuamong themselves and with any other SeniorNon Preferred Liabilities (as defined herein), (ii) junior to the Senior Higher Priority Liabilities (as defined herein) (and, accordingly, upon theinsolvency of Banco Santander, the payment obligations of Banco Santander in respect of principal under the Notes will be met after payment in full ofthe Senior Higher Priority Liabilities) and (iii)senior to any present and future subordinated obligations (créditos subordinados) of Banco Santander inaccordance 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 theNotes) acknowledges, accepts, consents to and agrees to be bound by the terms of the Notes related to the exercise of theBail-inPower (asdefined herein) set forth under“Description of Debt Securities—Agreement and Acknowledgement with Respect to the Exercise of theBail-inPower” in the accompanying prospectus. See“Notice to Investors”on pageS-iof 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 governmentalagency of the Kingdom of Spain, the United States or any other jurisdiction. Table of Contents We may redeem the Notes of any series, in whole but not in part, at 100% of their principal amount plus accrued and unpaid interest (if any)(i) atany time upon the occurrence of certain tax events, (ii)at any time upon the occurrence of certain regulatory events set forth herein or (iii)if 75% ormore of the initial aggregate principal amount of such series of Notes (which, for the avoidance of doubt, includes any additional issuances issuedsubsequently and constituting a single series of securities under the Base Indenture (as defined herein) as described under “Description of DebtSecurities—Additional Issuances” in the accompanying prospectus) have been redeemed or purchased by, or on behalf of, Banco Santander andcancelled. We may not redeem the Notes of any series under other circumstances, and there are no put rights with respect to the Notes of any series. See“Description of the Notes—Redemption and Repurchase.” 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-15 of this prospectus su