Sanofi Acquires Dynavax in $2.2 Billion Deal
Sanofi Acquires Dynavax; a $15.50 cash tender represents a 39% premium and may spur tendering ahead of a Q1 2026 close.
KEY TAKEAWAYS
- Sanofi offered $15.50 per share in a cash tender, valuing Dynavax at $2.2 billion.
- The offer represented a 39% premium to Dynavax's Dec. 23, 2025 closing price.
- Expected to close in Q1 2026 subject to HSR clearance and majority-tender conditions.
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Sanofi S.A. agreed to acquire Dynavax Technologies in a cash tender offer announced on December 24, 2025, adding the hepatitis B vaccine HEPLISAV-B and a shingles candidate to its adult immunization portfolio. The transaction is expected to close in the first quarter of 2026, subject to customary regulatory and tender conditions.
Deal Terms and Vaccine Assets
Sanofi offered $15.50 per Dynavax share in a cash tender offer, with any untendered shares converted at the same price in a post-tender merger. The offer represents a 39% premium to Dynavax’s closing price on December 23, 2025, and a 46% premium to the three-month volume-weighted average price as of that date. Dynavax’s board unanimously approved the agreement. The company retained Centerview Partners LLC and Goldman Sachs & Co. LLC as financial advisers and Cooley LLP as legal counsel. Sanofi said it will fund the purchase from available cash resources.
The acquisition adds HEPLISAV-B, a U.S.-marketed adult hepatitis B vaccine administered as a two-dose regimen over one month, compared with the standard three-dose, six-month schedule. It also includes Z-1018, a phase 1/2 shingles vaccine candidate, along with additional pipeline programs. Sanofi said the transaction will not affect its 2025 financial guidance.
Closing depends on the expiration or termination of the Hart-Scott-Rodino Act waiting period, certain foreign regulatory clearances, a majority tender of outstanding Dynavax shares, and other customary conditions. Thomas Triomphe, Sanofi’s executive vice president of vaccines, said, "Dynavax enhances Sanofi's adult immunization presence by adding differentiated vaccines that complement Sanofi's expertise."
