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.

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.