The FTSE 100 closed lower on Thursday, falling 16.59 points to 10,472.45, as investors digested fresh disappointment from AstraZeneca.
The pharmaceutical giant's shares were among the biggest decliners on the index, extending a sell-off that has already erased more than £20 billion from its market capitalization.
The FTSE 100's 0.2% drop marks a continuation of recent volatility, following a similar 21.
The decline followed the company's announcement that Wainua, its experimental treatment for heart disease, failed to meet its primary clinical endpoint in late-stage trials.
The setback at AstraZeneca proved sufficient to drag the broader index under European peers, which managed to hold steadier amid mixed global sentiment.
While the wider market showed resilience, the weight of the pharma giant's decline highlighted the concentrated risk large-cap healthcare names pose to the London benchmark.
The FTSE 100's 0.2% drop marks a continuation of recent volatility, following a similar 21.87-point decline on Friday driven by technology sector weakness.