SINGAPORE - The unexpected trading halt on the Singapore Exchange today brought back memories of the last time the local exchange had a major trading glitch.

Back in February 2007, its order engine seized up amid frenzied trading as investors reacted to the global selldown by dumping shares.

On the last day of February 2007, a host of problems plagued traders, including data that showed - incorrectly - buyers wanting to pay more for shares than sellers were asking.

Chaos reigned as a related service which updated stock prices went offline by late afternoon.

It led to an unprecedented event: closing prices were not available on SGX's own website or data provider Bloomberg even late in the evening after the trading session had ended.

The SGX website was blank with the usual prices and volume data absent.

Internet trading was also unreliable, dealers said, as the system became clogged by the biggest-ever trading day, in terms of value.

The SGX at the time blamed congestion for some anomalies in the trading system but insisted it had kept operating through the hectic day's trade.

Dealers said it was a lethal combination: 3.25 billion shares worth $4.03 billion being traded - and an index that was down by as much as 192 points.

The market had been spooked by the Dow Jones Industrial Average which had fallen by 416.02 points.