New York, Jan 20, 2026, 10:20 ET — Regular session.
- RAPT shares jumped roughly 64% to $57.54, closing in on GSK’s $58-a-share cash bid.
- GSK is acquiring the biotech to bring ozureprubart—a longer-acting anti-IgE drug—into its pipeline, currently under trial for food allergies.
- With a jam-packed week of data and earnings ahead, investors are zeroing in on the timing of tender offers and U.S. antitrust approvals amid market jitters.
Shares of RAPT Therapeutics soared roughly 64% on Tuesday, hitting $57.54 in early Nasdaq trading. The surge came after Britain’s GSK announced a cash purchase of the U.S. biotech at $58 per share.
RAPT is valued at $2.2 billion in the deal, giving GSK access to an experimental treatment for food allergies as drugmakers push to expand their immunology portfolios.
Wall Street’s key indexes dropped in early action amid fresh tariff threats, sparking a risk-off mood that highlighted the few winners tied to recent deals. “The headlines are going to drive angst and concern about what the future holds,” said David Lundgren, chief market strategist at Little Harbor Advisors. (Reuters)
Ozureprubart, a lab-engineered antibody targeting immunoglobulin E (IgE)—a major player in allergic responses—is at the heart of the buyout. GSK and RAPT have marketed the drug as a less frequent alternative to current anti-IgE injections.
GSK highlighted that “Ozureprubart offers the opportunity to bring sustained protection to patients with dosing every 12 weeks.” RAPT Chief Executive Brian Wong described the deal as “an attractive path forward for our programs.” GSK also noted that data from RAPT’s phase IIb prestIgE study is expected in 2027. (GSK)
GSK’s bid comes at a 65.2% premium over RAPT’s Monday close of $35.10. RAPT shares surged to $57.50 in U.S. premarket trading and stayed close to that level after hours. Jefferies analyst Michael Leuchten noted, “I like the fact that food allergy is not a crowded market at the moment.” On the other hand, Barclays analysts warned the asset is earlier-stage than they had anticipated for GSK, especially with looming HIV patent expiries. (Reuters)
A filing revealed that GSK’s U.S. subsidiary plans to start a cash tender offer for all outstanding RAPT shares within 10 business days after signing. The deal requires a majority of shares to be tendered and must clear the Hart-Scott-Rodino review, a U.S. antitrust process that enforces a waiting period before certain transactions can finalize. (SEC)
RAPT shareholders face limited near-term gains unless another bidder steps in—typical when a small biotech receives a full-cash offer at a hefty premium.
But closing isn’t guaranteed. Lengthy regulatory reviews, delays in the tender process, or potential lawsuits could push back the timeline. Plus, ozureprubart remains in mid-stage development — underscoring that GSK is investing now for data and commercial results that have yet to come.
Upcoming triggers include the release of the formal tender offer documents and RAPT’s board recommendation filing, which will precede the launch of the offer. Traders also face a busy U.S. economic calendar this week, with GDP, PMI numbers, and the PCE inflation report all on tap, alongside major earnings reports. Meanwhile, GSK anticipates wrapping up the deal in the first quarter of 2026.
