Trading on the Tokyo Stock Exchange was suspended yesterday morning after what is believed to have been a software glitch.
Because of the problem, stocks and bonds could not be traded until 1.30pm, leading to billions of pounds of lost trades.
The crash is the most serious since Tokyo adopted an all-electronic trading system in 1999 and ended floor trading.
The trading system is supplied by Fujitsu, which recently undertook a software upgrade to tackle an increase in the market’s trading volumes. That upgrade is believed to be linked to yesterday’s system failure.
US trading market Nasdaq suffered a temporary crash earlier this year, but that lasted only minutes.