Is Dynavax (DVAX) a Buy After Its Acquisition by Sanofi and Recent Price Surge?

The acquisition of Dynavax Technologies by Sanofi for $2.2 billion in late 2025 has sent ripples through the biotech sector, sparking debates about whether the stock remains a compelling investment. With Dynavax's share price surging 42% in the wake of the all-cash offer-valued at $15.50 per share, a 39% premium over its December 23 closing price-the question of valutive mispricing and growth potential looms large. This analysis examines the transaction's strategic rationale, Dynavax's financial trajectory, and the broader dynamics of the hepatitis B vaccine market to assess whether the stock still warrants a "buy" rating.

Strategic Rationale: A Defensive Move with Offensive Potential

Sanofi's acquisition of Dynavax is not merely a financial transaction but a calculated strategic pivot. By acquiring HEPLISAV-B, a two-dose adult hepatitis B vaccine, Sanofi gains a product that outperforms traditional three-dose regimens in terms of patient compliance and speed of administration. According to a report by , HEPLISAV-B's streamlined schedule could capture at least 60% of the U.S. adult hepatitis B vaccine market, projected to reach $900 million annually by 2030. This positions Sanofi to counter patent expirations in its core drug portfolio while expanding into high-margin specialty vaccines.

The deal also includes access to Dynavax's shingles vaccine candidate, Z-1018, which is in phase 1/2 trials and has demonstrated a 100% humoral response rate with fewer side effects than GSK's Shingrix according to . Analysts at FinancialContent argue that this acquisition aligns with Sanofi's "Play to Win" strategy, which prioritizes high-growth therapeutic areas like immunology and vaccines as detailed in their analysis. The integration of Dynavax's assets thus serves both defensive and offensive purposes, mitigating risk while opening new revenue streams.

Financial Metrics: Undervaluation and Growth Catalysts

Despite the 39% premium, Dynavax's pre-acquisition valuation appears to have been significantly undervalued. A discounted cash flow (DCF) analysis conducted by Yahoo Finance suggests the company was undervalued by approximately 57.3% based on future cash flow projections through 2029. This mispricing is partly attributable to its price-to-sales (P/S) ratio of 5.46x, which lags behind industry averages. However, the third-quarter 2025 financial results-$90 million in HEPLISAV-B revenue, a 13% year-over-year increase-underscore the company's strong cash-generating potential as reported.

The acquisition itself is structured to preserve Sanofi's financial flexibility. With $9.7 billion in cash reserves as of late 2025, the French pharmaceutical giant can fund the deal without compromising its 2025 guidance according to market analysis. For Dynavax shareholders, the all-cash offer provides immediate liquidity, but the long-term value of the assets (particularly Z-1018) may justify holding the stock if the deal closes in Q1 2026.

Market Dynamics: A Growing Pie and Competitive Edge

The hepatitis B vaccine market is poised for robust growth, with compound annual growth rates (CAGRs) ranging from 4.5% to 5.2% through 2032, according to industry reports. Dynavax's HEPLISAV-B is uniquely positioned to capitalize on this expansion due to its two-dose regimen, which reduces logistical barriers for healthcare providers and patients. Analysts at Fortune Business Insights note that combination vaccines, which HEPLISAV-B exemplifies, are increasingly favored for their efficiency in achieving seroprotection as observed.

However, competition remains fierce. GlaxoSmithKline's Engerix-B and Merck's traditional three-dose vaccines still dominate market share, but HEPLISAV-B's convenience and efficacy could erode their dominance. The addition of Z-1018 to Sanofi's pipeline further strengthens its competitive position, particularly if the shingles vaccine candidate demonstrates non-inferiority to Shingrix in phase 3 trials.

Analyst Sentiment and Risk Considerations

The market reaction to the acquisition has been largely positive. PredictStreet and FinancialContent both describe the deal as a "disciplined and thematically consistent expansion" that accelerates Sanofi's transformation into a biopharma powerhouse according to their analysis. Dynavax's CEO, Ryan Spencer, emphasized that the acquisition provides the global scale needed to maximize the impact of its vaccine portfolio as stated.

Yet risks persist. Regulatory hurdles could delay the deal's closure, and integration challenges might arise in harmonizing Dynavax's pipeline with Sanofi's existing operations. Additionally, while HEPLISAV-B's market potential is clear, Z-1018's development timeline remains uncertain. Investors must weigh these risks against the company's strong cash flow and strategic alignment with Sanofi's long-term goals.

Conclusion: A Buy with Caution

The acquisition of Dynavax by Sanofi represents a rare convergence of undervaluation and growth potential. While the 39% premium has largely corrected the stock's mispricing, the DCF analysis and market growth projections suggest that the company's intrinsic value remains underappreciated. For investors with a medium-term horizon, DVAX could still be a "buy," particularly if Z-1018 advances successfully through clinical trials. However, the all-cash structure and Sanofi's integration strategy will be critical factors to monitor. In a sector where innovation and execution often outpace expectations, Dynavax's assets-now under Sanofi's umbrella-offer a compelling case for cautious optimism.