The London Stock Exchange suffered a humiliating breakdown Monday, on what looked set to be one of the busiest trading days of the year.
The exchange fell over as dealers reacted to the dramatic economic news from the US where the government took control of mortgage groups Freddie Mac and Fannie Mae, in the biggest financial bailout in world history.
Trading was halted at 8.45 am and more than four hours later the problem had not been rectified.
The LSE said the system had been hit by a "connectivity issue" and insisted that the problem did not lie with its flagship TradElect trading platform.
The market is now in "auction phase," which means participants can decide on prices and place orders, but those orders will not be matched until system is live.
Traders are being asked to reconnect to the network. Once all traders have reconnected the exchange will give 15 minutes notice before going live.
The breakdown occurred just days after the LSE announced plans to improve services as it competes against a range of new entrants into the market.
Among LSE initiatives is a move to slash the time to complete a trade from six milliseconds to three as the exchange completes an upgrade of its 14-month old TradElect platform.
The exchange has also launched a server hosting service for investment banks to enable traders to reduce network latency and further cut the time to complete a trade. The Exchange Hosting service allows banks to move their servers into the exchange's own data center next to the LSE's TradElect trading platform. This shaves milliseconds off the time it takes to complete trades as it eliminates network latency, the exchange claimed.
The exchange has been upgrading TradElect to bolster its capacity and latency. The LSE said: "In September, current capacity on TradElect will initially double to 10,000 continuous messages per second. In October, it will double again to around 20,000 continuous messages a second and end-to-end execution latency on TradElect will be reduced by 50 percent from six milliseconds to three milliseconds."