London’s main share index, the FTSE 100, was down 1.3% at midday amid signs of more volatility on the markets.
It follows sharp losses for US shares on Friday, when the Dow Jones lost 2.5%, its biggest fall since June 2016.
On Friday the markets were spooked by strong US wage growth which raised the possibility of an accelerated pace of interest rate rises.
And there were early indications that US shares could fall further when trading begins on Monday.
In London, the FTSE 100 was down 95 points at 7,348. Earlier, the biggest markets in Asian fell between 1% and 2.5%.
However, those falls come after some very good years for investors.
The Dow Jones rose more than 25% in 2017 – a year which was also unusual for its lack of sharp moves.
“There is going to be more volatility this year, ” Andrew Wilson chief executive of Goldman Sachs Asset Management, told the BBC.
“We are in a cycle where central banks are reducing the number of bonds they are buying and some central banks putting up interest rates,” he said.
On Friday there was a hefty 4% loss for shares in Apple, which had been one of the markets’ stars performers in recent years.
That selling came despite a solid trading update from the company.