Company: SNY
Filing Date: 2025-10-29
Form Type: 424B5
Source: 0001193125-25-255563
Chunk: 99

Company: Sanofi
Filing Date: 2025-10-29
Form: 424B5
Chunk 99
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 immediately payable. This is called a declaration of acceleration of maturity. A declaration of acceleration of maturity may be canceled by the holders of at least a majority in principal amount of the outstanding debt securities of the affected series if certain conditions are met. ( Section 502) Except in cases of default, where the trustee has some special duties, the trustee is not required to take any action under the indenture at the request of any holders unless the holders offer the trustee reasonable protection from expenses and liability. This protection is called an indemnity. ( Section 603) If reasonable indemnity is provided, the holders of a majority in principal amount of the outstanding debt securities of the relevant series may direct the time, method and place of conducting any lawsuit or other proceeding seeking any remedy available to the trustee. These majority holders may also direct the trustee in performing any other action under the indenture. ( Section 512) Before you bypass the trustee and bring your own lawsuit or other formal legal action or take other steps to enforce your rights or protect your interests relating to the debt securities, the following must occur:

| • |     | You must give the trustee written notice that an event of default has occurred and remains uncured. |

| • |     | The holders of 25% in principal amount of all outstanding debt securities of the relevant series must make a                                                                          
 written request that the trustee take action because of the default, and must offer reasonable indemnity to the trustee against the cost and other liabilities of taking that action. |

| • |     | The trustee must have not taken action for 60 days after receipt of the above notice, request and offer of 
 indemnity.                                                                                                 |

| • |     | No direction inconsistent with such written request must have been given to the trustee during such 60-day period by holders of a majority in principal amount of all outstanding debt securities of that series. (Section 507) |

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Nothing, however, will prevent an individual holder from bringing suit to enforce payment.
(Section 508)

Street name and other indirect holders should consult their banks or brokers for information on how to give notice or direction to or make a request to the trustee and to make or cancel a declaration of acceleration.

We will furnish to the
trustee every year a written statement of certain of our officers certifying that, to their knowledge, we are in compliance with the indenture and the debt securities, or else specifying any default. (Section 1005)

Regarding the Trustee

We and several of
our