赛诺菲美股招股说明书(2025-10-27版)

$Floating Rate Notes due 20$Floating Rate Notes due 20$% Notes due 20$% Notes due 20$% Notes due 20 The notes offered by this prospectus supplement are (i)the $floating rate notes due 20(the “ 20floatingrate notes”), (ii) the $floating rate notes due 20(the “ 20floating rate notes” and, together with the20floating rate notes, the “floating rate notes”), (iii) the $% notes due 20(the “20fixed rate notes”),(iv) the $% notes due 20(the “20fixed rate notes”) and (v)the $% notes due 20(the“20fixed rate notes” and together with the “20fixed rate notes” and the “20fixed rate notes,” the “fixedrate notes”). We refer to the floating rate notes and the fixed rate notes collectively as the “notes.” The floating rate notes will bear interest at an interest rate for each interest period equal to Compounded SOFR (as definedherein), reset quarterly, plus a margin, subject to the provisions set forth in the “Description of the Notes—Principle, Interest andMaturity—Floating Rate Notes.” The margin applicable to the 20floating rate notes and the 20floating rate noteswill be% and%, respectively. We will pay interest on the floating rate notes on,,andof each year, beginning on, 2026. We will pay interest on the fixed rate notes onandof each year,beginning on, 2026. Interest on the notes will accrue from, 2025. The 20floating rate notes, the20floating rate notes, the 20fixed rate notes, the 20fixed rate notes and the 20fixed rate notes willmature at par on, 20, 20, 20, 20and 20, respectively. At our option, we may redeem the 20fixed rate notes in whole at any time or in part from time to time, at a redemptionprice equal to their principal amount plus a “make-whole” premium. At our option, we may redeem the 20fixed ratenotes (i)at any time prior to, 20(months prior to the maturity date of the 20fixed rate notes), inwhole at any time or in part from time to time, at a redemption price equal to their principal amount plus a “make-whole”premium and (ii)at any time on or after, 20(months prior to the maturity date of the 20fixed ratenotes), in whole at any time or in part from time to time, at a redemption price equal to 100% of their principal amount. At ouroption, we may redeem the 20fixed rate notes (i)at any time prior to, 20(months prior to thematurity date of the 20fixed rate notes), in whole at any time or in part from time to time, at a redemption price equal totheir principal amount plus a “make-whole” premium and (ii)at any time on or after, 20(months prior tothe maturity date of the 20fixed rate notes), in whole at any time or in part from time to time, at a redemption price equalto 100% of their principal amount. We may also redeem all of the notes at any time at a price equal to 100% of their principalamount in the event of certain tax law changes requiring the payment of additional amounts as described herein. In each case,we will pay accrued and unpaid interest, if any, and any other amounts payable to, but excluding, the date of redemption. Thefloating rate notes are not redeemable prior to maturity other than as set forth herein. The notes will not be subject to any sinking fund requirements. The notes will be issued in minimum denominations of $2,000and integral multiples of $1,000. See “Description of the Notes.” Table of Contents The notes will be our unsecured and unsubordinated obligations, and therefore will rank equally with each other and with all of our existing and futureunsecured and unsubordinated debt obligations. We do not intend to list the notes on any securities exchange or automated quotation system. Investing in the notes involves risks. Prior to making a decision about investing in the notes, you should carefullyconsider the specific factors that are described in the “RiskFactors” section beginning on pageS-15of this prospectussupplement and page 7 of the attached prospectus. None of the Securities and Exchange Commission, any state securities commission or any other regulatory body has approved or disapproved of thesesecurities or passed upon the accuracy or adequacy of this prospectus supplement or the attached prospectus. Any representation to the contrary is acriminal offense. The underwriters will deliver the notes to purchasers in book-entry form only through the facilities of The Depository Trust Company (“DTC”) for theaccounts of its direct and indirect participants (including Euroclear S.A./N.V. (“Euroclear”), as operator of the Euroclear System, and ClearstreamBanking S.A. (“Clearstream”)) against payment, expected to occur on or about, 2025. BofASecurities Barclays MUFG Table of Contents TABLE OF CONTENTS Prospectus Supplement CAUTIONARY STATEMENT REGARDING FORWARD-LOOKING STATEMENTSINCORPORATION OF INFORMATION WE FILE WITH THE SECSUMMARYTHE OFFERINGRISK FACTORSCAPITALIZATION AND INDEBTEDNESSUSE OF PROCEEDSDESCRIPTION OF THE NOTESTAXATIONUNDERWRITINGVALIDITY OF THE NOTESEXPERTS Prospectus EXPERTS As used herein, the terms “Sanofi,” the “Company,” the “Group,” “we,”