GSK to snap up Rapt Therapeutics in $2.2bn deal

(Sharecast News) - British drugs giant GSK has agreed to buy Rapt Therapeutics in a $2.2bn deal, it was announced on Tuesday, sending shares in the American allergy specialist soaring. Under the terms of the deal, GSK will pay Rapt shareholders $58 per share, giving the California-based firm an estimated aggregate equity value of $2.2bn. Net of cash acquired, GSK's estimated upfront investment is $1.9bn.

Shares in Rapt soared following the announcement. By 1230 GMT, the stock had put on 64% in pre-market trading.

GSK's London-listed shares were off 2% at 1,785.5p.

Loss-making Rapt is a clinical-stage biotech that specialises in developing new drugs for patients with inflammatory and immunologic diseases. Its portfolio includes ozureprubart, a long-acting anti-immunoglobulin monoclonal antibody in phase IIb trials.

The drug is intended to provide prophylactic protection against food allergens.

Currently around 17m people in the US have food allergies, with more than 1.3m people suffering severe reactions.

Tony Wood, GSK's chief scientific officer, said: "The addition of ozureprubart brings another promising new, potential best-in-class treatment to GSK's pipeline.

"Food allergies cause severe health impacts to patients, with existing treatments requiring injections as frequently as every two weeks. Ozureprubart offers the opportunity to bring sustained protection to patients with dosing every 12 weeks."

Brian Wong, Rapt chief executive, said the deal with GSK offered an "attractive path forward for our programmes".

Once completed, likely by the end of the current quarter, the blue chip will have global rights to ozureprubart excluding mainland China, Macau, Taiwan and Hong Kong.

Rapt was founded in 2015 and floated on Nasdaq in 2019. In the nine months to 30 September 2025, losses were $52.4m, compared to $76.6m a year previously, while research and development expenses were sharply lower, falling to $36.4m from $60.8m.

Russ Mould, AJ Bell investment director, said: "GSK is betting big on a potential breakthrough to help people with food allergies.

"There are still hurdles to clear in the testing process and no guarantee of success, yet these sorts of initiatives are exactly the risks that big pharma like GSK must take.

"Food allergies are a major concern. If GSK can crack the formula for a more convenient treatment, it stands to potentially make big bucks."