AstraZeneca shares plunge after heart drug trial fails

Shares of AstraZeneca plunged on Thursday, July 9, 2026, after the pharmaceutical company announced its drug Wainua failed to meet the primary goal in a late-stage clinical trial for a serious heart condition. The stock fell as much as 11 percent in London trading, erasing more than $20 billion in market value and marking one of the company's worst trading sessions in years.

The Phase III trial, named CARDIOTTRansform, evaluated whether adding Wainua to standard care could reduce cardiovascular deaths and recurrent heart-related events in patients with transthyretin-mediated amyloid cardiomyopathy (ATTR-CM). This progressive disease is caused by abnormal protein deposits that stiffen the heart muscle, leading to heart failure. The study involved 1,432 patients over 140 weeks but found no statistically significant benefit for the overall patient population.

AstraZeneca developed Wainua, a gene-silencing treatment, in partnership with U.S.-based Ionis Pharmaceuticals. Following the announcement, shares of Ionis also fell sharply. Wainua is already approved in more than 20 countries for a different condition, hereditary transthyretin-mediated polyneuropathy, and generated $212...