ASX reopens after glitch halts trading

The Australian Securities Exchange (ASX) has resumed trading after experiencing a "connectivity issue" for more than three hours this morning.

All systems were put into a state of "enquire" at about 10.05am as ASX technical staff investigated the issue with software vendor NASDAQ OMX.

A spokesman for the exchange explained that a "connectivity issue with the ASX trading system" caused some brokers to be unable to transact.

"Some of the participants were affected, but of course, ASX needs to operate a fair, orderly and transparent marketplace [so all trading had to be suspended]," the spokesman said.

At 1.30pm, the exchange advised brokers and software vendors that the issue had been resolved.

Trading resumed in stages, beginning with a practice market at 12.55pm.

Stock indices, derivatives, funds, interest rates, and various equity groups moved into pre-open at 1.40pm and opened between 2pm and 2.10pm.

The ASX has also determined all 6700 trades that took place before trading was suspended today to be valid.

All markets would close at 4pm as normal, it advised.

NASDAQ OMX has been contacted for comment