The blue-chip FTSE 100 was down 0.2pc, with the banking index tumbling 1.2pc on increased bets of negative interest rates.
The mid-cap FTSE 250 lost 0.3pc, snapping a three-day winning streak as a report also questioned positive data from an early-stage trial of a potential coronavirus vaccine.
"The market is in no-man's land," said Graham Secker, chief European equity strategist at Morgan Stanley.
"With not a whole lot of negative news, the market will not necessarily go down a lot, but at the same time it's not obvious what the new catalyst is to make it go materially higher other than medical advancement on the coronavirus."
The FTSE 100 has now recovered about 22pc from its March lows as governments and central banks launched historic stimulus measures to aid businesses and families impacted by a near standstill in activity due to the pandemic.
Britain's justice minister said on Wednesday the government will look at how it can help employees of engine maker Rolls-Royce after it said would cut at least 9,000 jobs and could shut some factories. Its shares fell 3.2pc in morning trading.
UK homebuilder Vistry Group Plc shed 3.2pc on forecasting more job cuts as it consolidates the operations of Bovis Homes and construction company Galliford Try's residential units.
But Playtech Plc surged 3.3pc after posting a jump in first-quarter profit as its financial trading division benefited from increased market volatility and trading volumes.
Retailer Marks & Spencer Group Plc rose 4.5pc as it said it would accelerate its latest turnaround programme after reporting a 21pc fall in annual profit.