Tokyo Stock Exchange suffered its worst-ever glitch on Thursday (October 1).
Trading was halted all day on the world’s third-biggest share market.
The exchange blamed the outage on a hardware problem in its ‘Arrowhead’ trading system.
It said there was also a subsequent failure to switch over to a backup system.
The glitch marked the first full-day suspension of the bourse since all-electronic trading began in 1999.
Smaller regional exchanges were also forced to suspend trading as they rely on the Tokyo systems.
Japan Exchange Group, which runs the TSE, said it would replace hardware as part of steps to fix the problem.
Supplier Fujitsu, which developed the trading system, says it is investigating what happened.
Tokyo’s roughly $6 trillion market ranks behind only New York and Shanghai.
In the past it had a reputation for technical problems and sluggish trading, but was seen to improve after new systems were introduced in 2010.