Dynavax Shares Surge 39% on $2.2 Billion Sanofi Buyout
French drugmaker pays a steep premium for Dynavax's growing Hepatitis B vaccine and a promising shingles candidate to challenge GSK's market leader.
Shares of Dynavax Technologies surged nearly 39% in morning trading after French pharmaceutical giant Sanofi announced it would acquire the vaccine maker in an all-cash deal valued at approximately $2.2 billion.
Sanofi agreed to pay $15.50 per share for Dynavax, representing a significant 39% premium to the stock's previous closing price. The news sent Dynavax (DVAX) shares soaring $4.27 to $15.40, just shy of the offer price and smashing through the stock's 52-week high. The deal underscores a strategic push by Sanofi to bolster its vaccines division with proven commercial products and high-potential pipeline assets.
The centerpiece of the acquisition is HEPLISAV-B, an adult hepatitis B vaccine that has rapidly gained market share since its approval. The vaccine's two-dose regimen over one month offers a significant advantage over older three-dose alternatives that require a six-month schedule. According to company filings, HEPLISAV-B has already captured 46% of the U.S. adult market, providing Sanofi with an immediate and growing revenue stream.
"Joining Sanofi will provide the global scale and expertise needed to maximize the impact of our vaccine portfolio," Ryan Spencer, Chief Executive Officer of Dynavax, said in a statement announcing the deal. "We are confident that this transaction – and the compelling value it provides – is in the best interests of the Company and its stockholders.”
Beyond the immediate revenue from HEPLISAV-B, Sanofi is also acquiring a strategic pipeline asset aimed at a lucrative market: a new shingles vaccine candidate. The investigational vaccine, known as Z-1018, is currently in Phase 1/2 trials. Early data suggests it could produce an immune response comparable to GSK's blockbuster Shingrix, but with a potentially more favorable tolerability profile. A successful entry into the multi-billion dollar shingles market would represent a major long-term victory for Sanofi.
This move positions Sanofi to directly compete with GSK, which has dominated the shingles vaccine space since Shingrix was introduced. Analysts see the acquisition as a clear strategic play to build a more robust and competitive adult immunization portfolio, leveraging Sanofi's global commercial infrastructure to accelerate the growth of the acquired assets.
The transaction has been unanimously approved by the boards of both companies and is expected to close in the first quarter of 2026, pending approval from Dynavax shareholders and regulatory clearance. With institutional investors holding over 98% of Dynavax's shares, the deal is widely expected to proceed smoothly. The acquisition of Dynavax and its assets aligns with Sanofi's broader "Play to Win" strategy, which focuses on deploying capital towards growth drivers and assets with the potential for market differentiation.