GSK Shares Slide Following $10.6bn Nuvalent Acquisition

Shares in GSK fell more than 3% in early Tuesday trading after the British pharmaceutical giant announced it had agreed to acquire Boston-based oncology biotech Nuvalent, Inc. in a deal valued at $10.6 billion (£8.0 billion), marking one of the largest acquisitions in the company’s history.

The acquisition values Nuvalent at $124 per share — a 40% premium to the biotech’s last closing price and a 26% premium to its 30-day volume-weighted average price. GSK will fund the transaction primarily through new and existing debt facilities, with net investment estimated at $9.4 billion after accounting for cash acquired. The deal is expected to close in Q3 2026, subject to regulatory approval under the Hart-Scott-Rodino Act.

The sell-off reflects typical market caution around large-scale M&A, with investors wary of the near-term earnings dilution flagged by GSK management. The company warned of low single-digit percentage dilution to core EPS for 2026, 2027, and 2028, with accretion to core operating profit not expected until 2027 and core EPS not until 2029.

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At the heart of the deal are two late-stage lung cancer drugs — zidesamtinib and neladalkib — described as potential best-in-class ROS1 and ALK inhibitors for non-small cell lung cancer (NSCLC). Both are currently under FDA review, with target decision dates of 18 September 2026 and 27 November 2026 respectively. A third asset, NVL-330, a potential best-in-class HER2 inhibitor, is currently in Phase I trials.

GSK CEO Luke Miels defended the acquisition, calling it a “multi-product deal” with “clinically proven targets” that could offer immediate new sales growth from 2027. The deal also accelerates GSK’s entry into lung cancer, providing a platform for expansion with Ris-Rez, its B7-H3 antibody-drug conjugate currently in Phase III development.

The company maintained its full-year 2026 guidance of 7–9% core operating profit and core EPS growth, and confirmed its commitment to a 70p dividend for 2026.