Sanofi to Acquire Dynavax for $2.2B, Boosting Vaccine Portfolio
The all-cash deal at a 39% premium adds a marketed Hepatitis B vaccine and a promising shingles candidate to Sanofi's pipeline.
French pharmaceutical giant Sanofi has announced a definitive agreement to acquire Dynavax Technologies in an all-cash deal valued at approximately $2.2 billion. The move is a strategic effort to strengthen Sanofi's vaccines business by adding Dynavax's marketed Hepatitis B vaccine and a promising shingles candidate currently in mid-stage development.
Under the terms of the agreement, Sanofi will acquire all outstanding shares of Dynavax for $15.50 each. This represents a significant 39% premium to Dynavax's closing stock price of $11.13 on December 23, 2025. Shares of Dynavax surged in pre-market trading to approach the acquisition price following the announcement.
The centerpiece of the acquisition is HEPLISAV-B, an adult hepatitis B vaccine that has gained market share in the U.S. with its two-dose regimen administered over one month. This offers a distinct advantage over the traditional three-dose, six-month regimens, providing faster protection for adults.
"Dynavax enhances Sanofi's adult immunization presence by adding differentiated vaccines that complement Sanofi's expertise," Thomas Triomphe, Executive Vice President of Vaccines at Sanofi, said in a statement. "Its marketed adult hepatitis B vaccine and shingles candidate bring new options to our portfolio and underscore our commitment to providing vaccine protection across the lifespan."
Beyond the immediate revenue from HEPLISAV-B, Sanofi gains a potentially valuable pipeline asset in Dynavax's shingles vaccine candidate, currently known as Z-1018. The candidate is in Phase 1/2 clinical trials, with early data suggesting it could offer comparable protection with better tolerability than the current market-leading shingles vaccine. This positions Sanofi to compete in the lucrative shingles market in the coming years.
The deal, which has been unanimously approved by the boards of both companies, is expected to close in the first quarter of 2026, pending customary closing conditions and regulatory approval.
For Dynavax, the acquisition offers a significant return for shareholders and a global platform for its products. The company's market capitalization stood at approximately $1.28 billion before the deal was announced.
"Joining Sanofi will provide the global scale and expertise needed to maximize the impact of our vaccine portfolio," said Ryan Spencer, Chief Executive Officer of Dynavax, in a company press release. "We believe Sanofi's commercial reach, development capabilities and commitment to evidence-based immunization will amplify the opportunity for HEPLISAV-B and our innovative pipeline to address important public health needs."
While the offer price provides a substantial premium, it sits below the consensus analyst price target of $19.25 for Dynavax stock, suggesting that Wall Street saw even greater long-term value in the company's standalone pipeline. This acquisition crystallizes that value for investors, providing certainty in an often-volatile biotech market. The transaction highlights a prevailing trend in the pharmaceutical industry, where large-cap companies are actively acquiring smaller, innovative biotechs to replenish their development pipelines and secure future growth engines.