LONDON, July 17, 2026, 10:09 BST — Shares in GSK plc (LON:GSK) experienced a sharp decline on Friday, shedding approximately £2.36 billion in market capitalization following disappointing phase III trial results for its chronic cough treatment, camlipixant. The stock dropped roughly 3% from Thursday's close, trading at 1,897p by mid-morning, while the broader FTSE 100 index remained relatively flat.
The setback marks a significant blow to GSK's pipeline ambitions. The CALM-1 study met its primary endpoint at week 12 with the 50 mg twice-daily dose, but CALM-2 failed to replicate those results at week 24. The 25 mg dose was ineffective in both trials, and key secondary endpoints were also missed. The company noted that treatment-related adverse events were comparable to placebo and that the modest efficacy was not sufficient to impact patient care meaningfully.
As a result, GSK has discontinued development of camlipixant for refractory chronic cough. However, a phase IIb study in irritable bowel syndrome (IBS) will proceed, as the mechanism may still hold promise for other indications.
The initial equity-value decline of £2.36 billion is particularly striking because it exceeds GSK's 2022 acquisition cost for BELLUS Health, the company that developed camlipixant, by approximately £765 million. GSK paid £1.6 billion ($2.0 billion) for BELLUS in 2023, with former chief commercial officer Luke Miels hailing camlipixant as a potential "best-in-class treatment" with "significant sales potential." The deal was predicated on a 2026 launch and adjusted EPS accretion beginning in 2027, both of which are now out of reach for the chronic-cough program.
Investors appear to be pricing in broader concerns beyond the specific trial failure. The market is effectively downgrading GSK's acquisition discipline and R&D effectiveness, as the loss exceeds the standalone value of camlipixant. This gap suggests skepticism about management's ability to execute on pipeline assets and integrate acquisitions successfully.
The timing of the setback is particularly sensitive. Just two days earlier, on July 15, GSK finalized its £8.0 billion acquisition of Nuvalent, a deal five times larger than the BELLUS purchase. CEO Luke Miels described the Nuvalent acquisition as one that "accelerates our entry into lung cancer." However, the combined impact of the trial failure and the large capital outlay raises questions about capital allocation and the company's strategic focus.
GSK reiterated its 2026 financial guidance on July 8, projecting sales growth of 3% to 5% at constant exchange rates and core EPS growth of 7% to 9%. The company did not issue updated earnings guidance following Friday's announcement, leaving investors to await the quarterly results on July 28 for clarity on potential impairments, shifts in R&D allocation, or changes to guidance.
The intraday decline of 59p across GSK's 4.008 billion shares underscores the market's swift reaction. While the share price could rebound before Friday's close, the risk of further pipeline setbacks or an impairment charge remains elevated. The Nuvalent acquisition, valued at £8.0 billion, now looms larger as investors scrutinize GSK's ability to deliver on its growth promises.
