The London Stock Exchange saw trading halted on hundreds of stocks twice on Tuesday after outages on the stock market.
Early in morning trading, it said it was only able to trade FTSE 100, FTSE 250 and IOB stocks following an “incident”.
The exchange said it was investigating the issue affecting its trading and information system.
The incident meant trading for hundreds of London-listed firms, such as Deliveroo and Asos, was halted for investors and traders.
Trading in these stocks stopped at about 9.15am. Shortly after 10am, London Stock Exchange Group (LSEG) said in a notice that trading across all its markets had resumed.
It did not disclose the cause of the issue.
The exchange continued to trade as normal until a second outage at around 11.20am once again stopped trading across smaller indices on the market.
At around 12.40pm, LSEG said it had returned to “regular trading” again after undertaking further investigations.
It was the second instances of outages affecting the London Stock Exchange in recent months.
In October, the exchange was hit by a roughly 80-minute outage which halted trading for hundreds of smaller stocks, with FTSE 100 and FTSE 250 shares once again unaffected.