Bosses at the London Stock Exchange (LSE) were left with red faces yesterday after a technical glitch brought trading down for the entire morning, the second time it has suffered IT problems in a week.
The group discovered a fault with the data feeds just minutes before the session was to open, which left some market participants unable to see up-to-date pricing. The fault forced it to halt trading for just over four hours, the biggest outage in London since November 2009.
Xavier Rolet, the chief executive of the LSE, was contrite: "We sincerely regret the inconvenience that today's disruption to trading has caused our customers."
The LSE switched to its new MillenniumIT trading system last week, and it has suffered a series of glitches causing brokers to complain that their websites were not showing correct market prices. This has led to some market participants referring to the "Millennium Bug".
When the markets failed to open as usual yesterday, the LSE posted a statement saying it was "investigating potential system issues during the opening auction call period". One trader at a large City firm said after the halt on the market that his colleagues "were just sitting around twiddling their thumbs".
He criticised the LSE for not keeping the market fully informed of what was happening: "We just wanted to know what's going on. This was pretty embarrassing for the LSE."
A spokeswoman for the exchange said: "In pre-market auction it became apparent that some people were seeing prices and others weren't." The LSE engineers found the problem and fixed it, allowing trading to open at 12.15pm.
This comes just three days after trading on the LSE's Italian market, Borsa Italiana, was also brought down for much of the day by a computer fault. The exchange did not get operations running until 3.30pm.
MillenniumIT has been running on the LSE's Turquoise trading venue since October, and several problems occurred on the first day. Since then, the spokeswoman said, it had run fairly smoothly.