ASX chief executive Dominic Stevens has apologies for a chaotic day on the Australian Stock Exchange, saying a hardware failure sparked a chain of problems that interrupted and ultimately ended trading prematurely.
"What happened today does not meet the high standards of operations and systems reliability that we set ourselves and that our customers should rightly expect of us," Mr Stevens said in a statement on Monday evening.
The ASX was forced to delay the start of trade until 1130 AEST on Monday and then halted trade shortly after lunch before announcing it would close the exchange for the day at 1537 AEST.
Mr Stevens said the "primary issue" behind the problems was a hardware failure in the main database used by the ASX trading system.
"This had a number of knock-on consequences that affected the operation of the market," he said.
"The issues were not in any way related to cyber security."
Mr Stevens said ASX was now "focused on ensuring that the market reopens on schedule tomorrow morning".
The Australian share market may have foregone up to $3.5 billion in turnover due to Monday's glitches.
The exchange operator initially delayed opening, saying there was a technical issue with a function that allows it to manage individual shares on its Nasdaq OMX equity trading platform.
The ASX then reported operational errors made it necessary to cancel transactions made in a 43 second window during market pre-open at 11:10 AEST.
CommSec market analyst Steven Daghlian said due to the delays and uncertainty only about $1.2 billion worth of shares were traded during the day, which was 20 per cent of the share value traded the previous Monday.
"It's been interrupted trade throughout the day so that's kept the value and volume very light today," he said.
"From the ASX200 as an index, it's just below 5,300 points still. So it's been pretty quiet overall. If we look at the actual percentage moves so far we're pretty flat and the market is still pretty close to its worst levels in 10 weeks.
"This is week six now that the market is in the red."
ASX was unable to comment on the cost of the delays or the loss in overall turnover, but said average daily turnover this year had been about $4.6 billion.
CMC Markets chief market analyst Ric Spooner doubted traders would have lost that much because there was no market moving news on Monday morning.
"There are two drivers of how business might be lost, one is how long the market was closed for and secondly is what news has happened during the period it has been closed," he told AAP.
"I'd say not a great deal has happened this morning, but we'll never know."
Federal Treasurer Scott Morrison said dealing with technical issues was a normal thing for companies in any advanced economy.
"It is one of the issues of dealing in a 21st century economy. We are more reliant on these systems than we ever have been," he told reporters.
