LONDON, July 17, 2026, 10:09 BST — Shares in GSK plc LON:GSK fell sharply after a failure in a cough treatment trial cut £2.4 billion from the company’s market capitalisation.
- London markets were open for trading. The standard session closes at 16:30 BST.
- GSK shares changed hands at 1,897p as of 10:01 BST, down roughly 3% from Thursday’s closing level.
- The initial equity-value decline reached £2.36 billion, amounting to 148% of the price GSK paid for BELLUS.
GSK plc LON:GSK shed roughly £2.36 billion in market value on Friday after mixed phase III data halted the camlipixant chronic-cough programme. The decline surpassed GSK’s 2023 acquisition cost for BELLUS by approximately £765 million.
This gap acts as a signal for investors. It indicates the market reduced value by more than just camlipixant’s independent worth. Investors also seem to be downgrading the credibility of acquisition discipline and R&D effectiveness.
Shares dropped 2% to 1,916p following the announcement, then slipped further to 1,897p by 10:01 BST. The FTSE 100 remained largely unchanged. Selling pressure increased afterwards.
| Comparison | Figure | Investor reading |
|---|---|---|
| Friday share movement | Down roughly 3% at 1,897p | FTSE 100 climbed 0.03% |
| Initial equity-value decrease | £2.36 billion | Drop of 59p across 4.008 billion shares |
| BELLUS acquisition cost | £1.60 billion | Loss surpasses buyout by £0.76 billion |
| Nuvalent acquisition price | £8.0 billion | Value is five times the BELLUS purchase |
The figure is based on 4.008 billion shares as of the end of the second quarter, reflecting Friday’s 59p drop from Thursday’s close of 1,956p. The provisional total is £2.36 billion.
CALM-1 achieved its main goal at week 12 with the 50 mg twice-daily dose. CALM-2 did not reach this target at week 24. The 25 mg dose was unsuccessful in both studies.
Both trials failed to meet key secondary endpoint targets. The rate and severity of treatment-related adverse events were comparable to placebo.
GSK stated the modest effectiveness was not expected to significantly impact patient treatment. The company has discontinued development for refractory chronic cough. However, a phase IIb study in irritable bowel will proceed.
GSK acquired BELLUS for $2.0 billion, later paying £1.6 billion, in 2023. At the time, Luke Miels served as chief commercial officer. He described camlipixant as a possible “best-in-class treatment” offering “significant sales potential.” GSK
The agreement was based on a 2026 launch and expected adjusted EPS accretion starting in 2027. These targets are now out of reach for the chronic-cough program.
The notice issued on Friday did not provide updated earnings guidance. GSK reiterated its 2026 forecast on July 8, maintaining an expected sales increase of 3% to 5% at constant exchange rates and projecting core EPS growth of 7% to 9%.
Capital allocation has gained significance. GSK finalised its £8.0 billion acquisition of Nuvalent on July 15. Chief Executive Miels said this “accelerates our entry into lung cancer.” The amount paid is five times higher than the price of BELLUS. GSK
The next official update comes with quarterly results on July 28. Investors are expected to look out for any impairments, shifts in R&D allocation or changes to guidance.
Risks: The £2.36 billion amount refers to an intraday change, rather than an accounting write-off. Shares might rebound prior to Friday’s market close. However, a new impairment or another pipeline setback may increase pressure.
