It later said the outage was caused by a software issue limited to the trading of multiple securities in a single order – known as combination trading – which created inaccurate market data.
Trading was called off for the day at 3pm.
“ASX and its technology provider Nasdaq have identified the root cause and a resolution path to fix it,” a spokesman for the market operator said on Monday afternoon.
Measures were in place to allow normal trading on Tuesday morning, the market operator said in a status update.
It was the worst trading outage for the ASX since 2016, and the latest technical snafu for the market operator, which suffered a number of difficulties – such as company announcements failing to load on the morning it relaunched its new website.
Brokers, fund managers, and company executives spoke of disappointment and frustration. Some said they simply filled in their time with research, ringing clients, or visiting the gym.
“It is frustrating for any participant in the market,” chief investment officer for Australian Eagle Asset Management, Sean Sequeira, said.
“They have had a few hiccups in the last little while with their systems. Everyone in the market wants to ensure they have a reliable exchange.”
A number of traders noted that Monday’s outage came after the go-live of the ASX Trade Refresh production platform on Monday morning.
Migration activities for the upgrade apparently occurred on Saturday.
The ASX 200 rose as much as 1.3 per cent to 6487.3 in what little time it had on Monday – the highest intraday mark since early March. It finished 1.2 per cent higher at 6484.3, its best close since February 27.
Wall Street’s lead was strong after US markets finished higher on Friday despite concern over the spread of COVID-19 across the country.
Senior investment advisor with Shaw & Partners, Adam Dawes, said trading was difficult as soon as the market opened on Monday.
“We were placing orders at 10.15am and 10.20am and they were failing. We were continually trying to push them through. We were having problems from the get-go,” he said.
It is the third time the ASX has halted trading in the past five years. The most recent outage was on 5 June, 2018, when the futures platform dropped out at 4.55pm. But the whole market was last halted in September 2016, when a hardware failure stopped the market opening at 10am.
It eventually opened at 11.30am, but was forced to close early at 2.05pm. It resumed trading as normal the next day.
Cybersecurity issues forced the New Zealand stock exchange to halt trading in a number of sessions in late August and early September, while a typhoon delayed trade on Hong Kong’s Hang Seng last month. A spokesman for Australian Signals Directorate referred queries about a potential cyber attack back to the ASX, implying it had not been informed about any external security problems.
Japan’s Nikkei suffered technical problems on September 30 and was forced to halt.
The outage also affected two companies that were expecting to debut on Monday – Native Mineral Resources and Universal Store.
“It’s a little disappointing, but it is what it is I guess,” Universal Store’s interim chief financial officer Eddie MacDonald said.
Chief economist at BetaShares ETFs David Bassanese said the incident did not reflect particularly well on the ASX.
“Obviously it is not a good look,” he said.
“They want to be able to at least provide an operating market.”
Burman’s Julia Lee said many traders would be lamenting that the outage happened on a day that looked destined for big gains.
“Luckily for the ASX, Monday’s tends to be a low liquidity day, because we’re following on from last week’s lead,” Ms Lee said.
“But undoubtedly most traders would have prefered this happen on a down day rather than an up day.”