Company: SNY
Filing Date: 2025-10-29
Form Type: 424B5
Source: 0001193125-25-255563
Chunk: 13

Company: Sanofi
Filing Date: 2025-10-29
Form: 424B5
Chunk 13
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| Regular Record Dates | Close of business on April 18 and October 19 |

| Day Count Convention | Interest on the fixed rate notes will be calculated on the basis of a 360-day year consisting of twelve 30-day months. |

| If any payment is due on the fixed rate notes on a day that is not a business day (as defined in “Description of the Notes” in this prospectus supplement), we will make the payment on the day that is the                                           
 next business day. Payments postponed to the next business day in this situation will be treated as if they were made on the original due date. Postponements of this kind will not result in a default, and no interest will accrue on the postponed 
 amount from the original due date to the next day that is a business day.                                                                                                                                                                             |

(1) (a) the sum of the present values of the Remaining Scheduled Payments of principal and interest thereon discounted to the redemption date (assuming the relevant Notes matured on the Par Call Date) on a semi-annual basis (assuming a 360-dayyear consisting of twelve 30-daymonths) at the Treasury Rate plus (i) 0.050% (or 5 basis points), in the case of the 2028 Fixed Rate Notes; and (ii) 0.100% (or 10 basis points), in the case of the 2032 Fixed Rate Notes; less (b) unpaid interest, if any, accrued thereon to the date of redemption, and (2) 100% of the principal amount of the notes to be redeemed,

| plus, in either case, accrued and unpaid interest thereon to the redemption date (but not including the redemption date). |

| On or after the applicable Par Call Date, the Issuer may redeem the relevant series of the 2028 Fixed Rate Notes and the 2032 Fixed Rate Notes, in whole or in part, at any time and from time to time, at a redemption                
 price equal to 100% of the principal amount of the relevant series of the 2028 Fixed Rate Notes and the 2032 Fixed Rate Notes being redeemed, as applicable, plus accrued and unpaid interest thereon to the relevant redemption date. |

| The Issuer may redeem the 2027 Fixed Rate Notes at its option, in whole or in part, at any time and from time to time, at a redemption price (expressed as a percentage of principal amount and rounded to three decimal 
 places) equal