Shares of pharmaceutical giant GSK opened lower in London on Thursday, February 19, 2026, declining 0.4% to 2,259 pence by 0901 GMT. The movement was attributed to two concurrent factors: the stock trading ex-dividend and the market's reaction to newly released real-world data for the company's respiratory syncytial virus (RSV) vaccine, Arexvy.
Dividend Mechanics and Share Price Pressure
The stock officially went ex-dividend on Thursday, meaning new buyers are no longer entitled to the upcoming quarterly payout. Data from Hargreaves Lansdown confirmed the ex-dividend date, setting the stage for an 18 pence per share distribution scheduled for April 9. It is a standard market mechanism for a share price to adjust downward on its ex-dividend date to reflect the value of the forthcoming cash payment being removed from the company's assets. Notably, the share price decline of 0.4% was less than the full 18 pence dividend amount, leading traders to debate whether the vaccine data also contributed to the downward pressure.
Arexvy Real-World Data Shows Promise
Concurrently, GSK released a significant set of real-world data for Arexvy, which it plans to present in detail at the RSVVW'26 conference in Rome. The findings come from a large U.S. retrospective claims study involving over 2.5 million adults aged 60 and older. According to the study, Arexvy demonstrated a 75.6% effectiveness rate in preventing RSV-related hospitalizations. Perhaps more notably, the vaccine was also associated with a 63.1% reduction in the incidence of major adverse cardiovascular events (MACE), such as heart attack and stroke, during hospitalizations linked to RSV.
Deepak L. Bhatt of Mount Sinai commented that the data suggests RSV vaccination "could help reduce the risk of certain serious RSV-related outcomes." Christian Felter of GSK pointed to the results as supporting "the value of our RSV vaccine." The company did, however, include a standard caveat, noting the observational nature of the study means it can show association but cannot definitively prove causality. Further analysis could refine these findings or reveal they apply to specific patient subgroups.
Market and Competitive Context
The RSV vaccine market for older adults has become increasingly competitive in the United States, where GSK's Arexvy faces direct competition from Pfizer's Abrysvo and Moderna's mRESVIA, all cleared by the U.S. Food and Drug Administration. Investors are closely scrutinizing Arexvy's performance and potential market share, especially with the next RSV season approaching. GSK's shares had reached a 52-week high of 2,282 pence just a day prior and have appreciated approximately 57% over the past year, placing vaccines firmly back in the spotlight for the company.
Corporate Actions: Buybacks and Treasury
In a separate regulatory update on Wednesday, GSK disclosed it had repurchased 420,000 of its own shares on February 17 as part of an ongoing buyback program. The company paid a volume-weighted average price of 2,231.39 pence per share and will hold the repurchased stock in treasury. Market participants are watching for further updates on the company's capital return strategy, including future buyback activity and the confirmed April 9 dividend payment, a key date for income-focused shareholders.
Broader Market Sentiment
The trading session occurred against a backdrop of general softness in European equities. Broader indices faced pressure from a mixed batch of corporate earnings reports and escalating geopolitical tensions between the U.S. and Iran, factors that can overshadow even typically defensive sectors like healthcare. Investors now await additional data presentations from the RSV conference and any new guidance from GSK regarding its vaccine strategy and shareholder returns, which will be critical for the stock's trajectory in the coming weeks.
