Company: SNY
Filing Date: 2025-10-27
Form Type: 424B5
Source: 0001193125-25-250786
Chunk: 101

Company: Sanofi
Filing Date: 2025-10-27
Form: 424B5
Chunk 101
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 could change their rules and procedures at any time. As used in this section, any reference to securities also refers to book-entry securities issued in respect of securities in bearer form. The Clearing Systems DTC We understand that DTC is:

| • |     | a limited-purpose trust company organized under the New York Banking Law; |

| • |     | a “banking organization” within the meaning of the New York Banking Law; |

| • |     | a member of the Federal Reserve System; |

| • |     | a “clearing corporation” within the meaning of the New York Uniform Commercial Code; and |

| • |     | a “clearing agency” registered pursuant to the provisions of Section 17A of the Exchange Act. |

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DTC holds securities for its participants (“Direct Participants”) and
facilitates the clearance and settlement of securities transactions between participants through electronic computerized book-entry transfers and pledges between Direct Participants’ accounts. This eliminates the need for physical movement of
securities certificates. Direct Participants include both U.S. and non-U.S. securities brokers and dealers, banks, trust companies, clearing corporations, and certain other organizations.

DTC is a wholly-owned subsidiary of The Depository Trust & Clearing Corporation. Access to the DTC system is also available to others
such as both U.S. and non-U.S. securities brokers and dealers, banks, trust companies, and clearing corporations that clear through or maintain a custodial relationship with a Direct Participant, either
directly or indirectly (“Indirect Participants”).

The DTC Rules applicable to its participants are on file with the SEC.

Clearstream

We
understand that Clearstream is registered as a bank in Luxembourg and as such is subject to regulation by the Commission de Surveillance du Secteur Financierand the Banque Centrale du Luxembourg, which supervise and oversee the
activities of Luxembourg banks.

Clearstream holds securities for its participants and facilitates the clearance and settlement of
securities transactions among them. It does so through electronic book-entry changes to the accounts of its customers. This eliminates the need for physical movement of certificates.

In addition to the clearance and settlement of internationally traded securities, Clearstream provides its participants, among other things,
safekeeping, administration, clearance and securities lending and borrowing services. It interfaces with the domestic markets in several countries.

Clearstream’s participants include worldwide financial institutions, including underwriters, securities brokers and dealers, banks,
trust companies and clearing corporations and certain professional financial intermediaries. Its