Company: SNY
Filing Date: 2025-03-21
Form Type: S-8 POS
Source: 0001193125-25-059686
Chunk: 1

Company: Sanofi
Filing Date: 2025-03-21
Form: S-8 POS
Chunk 1
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278502 (the “Registration Statement”), is being filed to deregister certain shares of Sanofi (the “Registrant”) Ordinary Shares (the “Shares”) that were registered for issuance pursuant to the
Action 2024 Shareholding Plan (the “2024 Plan”). The Registration Statement, which was filed with the Securities and Exchange Commission on April 4, 2024, registered 400,000 Shares issuable pursuant to the 2024 Plan. The Registration
Statement is hereby amended to deregister the 145,917 Shares that were previously registered and that remain unissued under the 2024 Plan.

SIGNATURES THE REGISTRANT.Pursuant to the requirements of the U.S. Securities Act of 1933, as amended, the registrant certifies that it has reasonable grounds to believe that it meets all of the requirements for filing on Form S-8and has duly caused Post-Effective Amendment No. 1 to be signed on its behalf by the undersigned, thereunto duly authorized, in the City of Paris, France on March 20, 2025.

| SANOFI |     |                                           |
| By:    |     | /s/ Roy Papatheodorou                     |
| Name:  |     | Roy Papatheodorou                         |
| Title: |     | Executive Vice President, General Counsel |

Note: In reliance upon Rule 478 under the U.S. Securities Act of 1933, as amended, no other person is required to sign this Post-Effective Amendment No. 1.