A technical glitch delayed the start of trading Friday on the UK's blue chip FTSE 100.
Investors were forced to withhold trades on the London Stock Exchange for nearly two hours.
Making it the longest outage at one of the world's top bourses in eight years.
The LSE said it suffered a 'technical software issue'.
In a statement on its website Friday, the Stock Exchange said it was still investigating the issue.
The fault affected hundreds of shares in some of the UK's largest firms - including Shell, Unilever and HSBC - worth a total of $2.8 trillion.
The outage came during a hectic week for traders as global financial markets soured on worries over a possible U.S. recession.
It's the second outage at the LSE in just over a year.
The opening auction was delayed due to a technical fault in June 2018, but trading resumed after an hour.