Dynavax Technologies Corporation (NASDAQ: DVAX) is the standout mover heading into the Christmas break after Sanofi agreed to acquire the vaccine maker in an all-cash deal valued at about $2.2 billion. The transaction price — $15.50 per share in cash — instantly re-framed DVAX from a “biotech fundamentals” story into a deal-arbitrage stock, with trading now anchored around the buyout price. 1
A timing note that matters for anyone planning “tomorrow” trades: U.S. equities had a holiday early close today (Dec. 24) at 1:00 p.m. ET, and the market is closed Thursday, Dec. 25 for Christmas. The next regular U.S. equity session is Friday, Dec. 26. 2
What happened to DVAX after the bell today
In late trading following today’s shortened session, DVAX was around $15.38 with heavy volume and a wide intraday range as the market rapidly priced in the cash offer. As of 19:35 UTC (post-close), DVAX showed an intraday high near $15.71, low around $14.50, and volume above 30 million shares.
Reuters described DVAX shares as up roughly 39% in U.S. trading on the day, trading around $15.45 at the time of its report — essentially right on top of the $15.50 bid, as often happens when a definitive cash deal is announced. 1
The single driver: Sanofi is buying Dynavax for $15.50 per share
The move is tied directly to today’s acquisition announcement:
- Buyer: Sanofi
- Target: Dynavax Technologies
- Consideration:$15.50 per share in cash
- Implied equity value: about $2.2 billion
- Timing: expected to close in Q1 2026 (subject to customary conditions) 3
Sanofi’s strategic rationale is centered on vaccines — adding Dynavax’s marketed HEPLISAV‑B adult hepatitis B vaccine and gaining Dynavax’s shingles vaccine candidate (Z‑1018), which is in Phase 1/2 development. 3
Why DVAX is now trading slightly below $15.50
When a deal is cash and definitive, the target stock typically trades near but not exactly at the offer price. That gap (the “spread”) reflects:
- Time value (investors are waiting until closing to receive cash)
- Deal risk (regulatory approvals, tender participation, and other closing conditions)
- Holiday liquidity (today’s shortened session can amplify small dislocations)
The key takeaway for the next session: DVAX’s day-to-day movement is now more about deal probability and timeline than biotech sentiment, unless new information changes the odds of closing (or a competing bid emerges). 4
Deal structure investors should understand before the next open
This is structured as a cash tender offer followed by a merger “back-end” step:
- Sanofi expects to commence a tender offer for all outstanding DVAX shares at $15.50. 3
- The Dynavax board unanimously approved the transaction. 4
- Closing is subject to customary conditions, including:
- Tender of at least a majority of outstanding shares
- Expiration/termination of the Hart‑Scott‑Rodino waiting period (antitrust)
- Certain foreign regulatory filings/clearances, and other conditions 4
- Importantly, today’s announcement materials emphasize the tender offer has not yet commenced, and that formal tender documents will be filed with the SEC (Schedule TO) along with Dynavax’s recommendation statement (Schedule 14D‑9). 4
For readers thinking about action “tomorrow”: the most market-moving near-term updates are likely to be SEC filings and tender-offer launch details, which can hit the tape even when the market is closed. 4
Analyst and commentary reaction from today: quick downgrades, “deal mode” ratings
Once a definitive cash offer is on the table, it’s common for analysts to shift ratings toward neutral language because upside becomes capped near the deal price.
- William Blair downgraded DVAX to Market Perform from Outperform after the Sanofi deal, according to The Fly’s coverage on TipRanks. 5
- MarketBeat likewise reported a William Blair “market perform” stance and highlighted that many pre-deal targets/ratings become less actionable in a takeout scenario. 6
One important nuance: you may still see older “12‑month price targets” published across finance sites (often well above the deal price). Those targets were largely built for a standalone Dynavax valuation and are typically superseded by a cash deal unless the transaction fails or a higher bid appears. 6
What Sanofi is buying: HEPLISAV‑B and a shingles candidate
Understanding the assets helps explain why a large pharma would pay a premium:
HEPLISAV‑B (adult hepatitis B vaccine)
Sanofi and other reporting emphasized HEPLISAV‑B’s differentiation: an adult hepatitis B vaccine administered as two doses over one month, versus traditional three-dose schedules over six months. 3
Reuters reported HEPLISAV‑B generated $90 million in sales in Q3 2025, and noted that analysts have modeled meaningful peak U.S. sales potential. 1
Sanofi also pointed to a large adult opportunity in the U.S., citing nearly 100 million adults born before 1991 who remain unvaccinated. 3
Z‑1018 (shingles vaccine candidate)
The deal also includes Dynavax’s Z‑1018 shingles candidate in Phase 1/2 development. 3
Reuters cited commentary that the candidate could become a meaningful longer-term contributor if early signals hold up in larger studies, with the shingles market currently dominated by GSK’s Shingrix. 1
Market context today: a thin, holiday-shortened session amplified the move
DVAX’s catalyst was company-specific, but today’s tape also featured holiday-thinned liquidity and a broad market drift higher into year-end. Reuters reported major U.S. indexes finished higher in the shortened session as part of a “Santa rally” narrative — a backdrop that can sometimes boost risk appetite and momentum chasing around big headlines. 7
What to watch before the next U.S. market session
Because Dec. 25 is a full U.S. market holiday, the practical checklist is “what to know before Friday, Dec. 26.”
1) Any SEC filing that starts the tender-offer clock
The next concrete milestone is the formal tender-offer launch and the associated SEC documents (Schedule TO and 14D‑9). Those filings often clarify key mechanics, timelines, and conditions in plain English. 4
2) Where DVAX trades relative to $15.50
If DVAX trades meaningfully below $15.50, the market may be pricing:
- Longer time-to-close
- Higher perceived regulatory/closing risk
- General risk-off conditions
If DVAX trades at or above $15.50, the market may be signaling either:
- Very high confidence of closing plus carry/technical effects, or
- Some probability of a higher competing bid (not the base case, but this is what “above-offer” trading often implies)
3) Regulatory headlines and deal-condition updates
This transaction includes standard antitrust/tender conditions, so any news about regulatory timing can move the spread. 4
4) Earnings calendar — likely less important near-term, but still on the radar
Several market calendars list Dynavax’s next earnings report around Feb. 19, 2026 (timing can shift, and deal progress could change what matters), but it remains a scheduled marker investors watch if the acquisition has not closed by then. 8
Bottom line for DVAX going into the holiday break
After the bell on Dec. 24, 2025, Dynavax is no longer trading primarily on biotech “upside.” It’s trading as a takeout target with a defined cash value of $15.50 per share, and the market’s job from here is to price time, probability, and risk until closing — expected in Q1 2026. 3
With U.S. markets closed on Dec. 25, the most actionable “before the next open” work is simple: watch for tender-offer commencement filings, monitor any regulatory timeline updates, and track whether DVAX continues to trade tightly around the offer price when trading resumes on Friday, Dec. 26. 2
