In a significant strategic move, FTSE 100 pharmaceutical leader GSK has announced a major acquisition, agreeing to purchase the US biotech company Rapt Therapeutics for a substantial $2.2bn (£1.6bn).
The deal, confirmed on Tuesday 20 January 2026, represents the first major strategic play by GSK's new chief executive, Luke Miels, who took the helm just weeks ago. It underscores the company's aggressive push to bolster its pipeline in immunology and inflammatory diseases.
Deal Details and Strategic Rationale
GSK will pay $58 per share for California-based Rapt, a premium of nearly double the company's closing Nasdaq price of $33.81 from the previous day. The transaction involves an upfront investment of $1.9bn and is anticipated to be finalised in the first quarter of 2026.
Central to the acquisition is GSK securing the global rights to Rapt's ozureprubart programme, an experimental therapy designed to treat food allergies. The rights exclude mainland China, Hong Kong, Taiwan, and Macau. GSK will also assume responsibility for royalty payments related to ozureprubart owed to RAPT's partner, Shanghai Jeyou Pharmaceutical Co.
Tony Wood, GSK's chief scientific officer, highlighted the strategic fit, stating the drug brings a "promising new, potential best-in-class treatment" to the company's development pipeline. He emphasised that ozureprubart aligns with GSK's strategy to acquire assets that tackle validated targets where a clear unmet medical need exists.
Market Reaction and Broader Reshuffle
Following the acquisition news, GSK's share price experienced a dip, falling 1.24 per cent to 1793.49 pence. Meanwhile, Brian Wong, President and CEO of Rapt Therapeutics, noted the deal would allow his firm to leverage GSK's extensive resources, global infrastructure, and commercialisation capabilities.
In a related development within the GSK ecosystem, the company also confirmed that Japanese pharmaceutical firm Shionogi & Co will buy out Pfizer's 11.7 per cent stake in their HIV specialist joint venture, ViiV Healthcare. Shionogi is investing $2.1bn for new shares, increasing its stake to 21.7 per cent, while Pfizer exits with $1.8bn. GSK will retain its 78.3 per cent controlling interest.
David Redfern, Chair of ViiV Healthcare, said the agreement simplifies the shareholder structure and allows the collaboration with Shionogi on long-acting injectable HIV treatments to continue.
Looking Ahead
This dual announcement signals a period of active portfolio management for GSK under its new leadership. The Rapt acquisition directly feeds into its core therapeutic areas, with crucial trial data for the ozureprubart food allergy programme expected next year. The reshuffle at ViiV Healthcare streamlines its ownership, potentially allowing for more focused development in the competitive HIV sector.
