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

Company: Sanofi
Filing Date: 2025-10-29
Form: 424B5
Chunk 10
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sanofi.com; or the following telephone number: +33 1 53 77 40 00.

The 2024 Form 20-F and any other information incorporated by reference is considered to be a part of
this prospectus supplement and the attached prospectus. The information in this prospectus supplement, to the extent applicable, automatically updates and supersedes the information in the 2024 Form 20-F.

We have not, and the underwriters have not, authorized any other person to provide you with any information, other than the information contained or incorporated by reference in this prospectus supplement, the attached prospectus and any related free-writing prospectus we prepare or authorize, and we take no responsibility for any other information that others may give you. We are not, and the underwriters are not, making an offer to sell these notes in any jurisdiction where the offer or sale is not permitted. You should not assume that the information appearing in this prospectus supplement, the attached prospectus and the documents incorporated by reference herein or therein, is accurate as of any date other than the date on the front of these documents. Our business, financial condition, results of operations and prospects may have changed since that date.

S-5

SUMMARY

This summary does not contain all of the information that may be important to you. You should read carefully the entire prospectus supplement, the attached prospectus and the additional documents incorporated by reference herein for more information about us.

Overview

We are a leading global healthcare company, focused on patient needs and engaged in the research, development, manufacture and marketing of
therapeutic solutions. In 2024, our net sales amounted to €41,081 million. Sanofi is the parent of a consolidated group of companies. We have one operating segment: Biopharma. It comprises commercial operations and research, development
and production activities relating to the Specialty Care, General Medicines and Vaccines franchises plus support and corporate functions, for all geographical territories. Sanofi’s activities are organized around the following categories:
DUPIXENT, Neurology & Immunology, Rare Diseases, Oncology, Rare Blood Disorders, General Medicines Core Assets and Non-Core Assets and Vaccines.

Acquisitions

On July 17, 2025,
Sanofi completed its acquisition of Blueprint Medicines Corporation (“Blueprint”), a U.S.-based, publicly traded biopharmaceutical company specializing in systemic mastocytosis (“SM”), a rare immunological disease, and other KIT-driven diseases. The acquisition includes