The FTSE 100 edged lower on Thursday, lagging its European peers as heavyweight AstraZeneca weighed heavily on the index.
The pharmaceutical giant, the FTSE 100's second-largest constituent, plunged 7.3% after its gene-silencing therapy Wainua, developed with Ionis Pharmaceuticals, failed a late-stage clinical trial aimed at reducing heart complications in patients with a rare cardiac condition.
Energy stocks also added to the pressure, with Shell falling 1.3% and BP losing 1.9% as crude oil prices retreated.
Investors remained focused on developments in the Middle East, where uncertainty surrounding the US-Iran ceasefire continued to fuel concerns over energy supplies and inflation.
Elsewhere, Severn Trent said trading remained in line with expectations after a strong start to its 2027 financial year.
Meanwhile, the latest RICS survey showed UK house prices continued to decline in June, although the pace of falls eased slightly, suggesting the housing market may be stabilising.