Security group G4S was the biggest faller on the FTSE 100 in Wednesday morning trading despite reporting a 7.6% rise in first-half profit.
The firm saw its shares slide 5.3% after chief executive Ashley Almanza said it would sell off more underperforming assets this year.
Overall, the 100-share index was down 52.77 points or 0.7% at 7,489.96.
Meanwhile, the pound rose 0.05% against the dollar to exactly $1.30 and was up 0.26% against the euro to 1.1084 euros.
Among the top gainers was payment processing firm Worldpay, which added 0.2% after agreeing to merge with US rival Vantiv.
Biggest winners were mining firms Fresnillo and Randgold Resources, which gained 3% and 2.4% respectively.
On Tuesday, the FTSE 100 narrowly failed to hit a record closing high after a late rally stalled just short of the magic mark.