The Australian Securities Exchange (AS) has blamed an "unprecedented" hardware failure for problems on Monday that forced the bourse to open late and close early.
Monday's opening was delayed by more than an hour by the failure, with a series of knock-on consequences affecting trading throughout the day until a decision was made to shut up shop an hour and a half early.
In a statement, ASX CEO Dominic Stevens apologises for the "unacceptable" outage, which he says was "complex and unprecedented". He also defended the decision to close the market.
The exchange's report (PDF) into the problem says that the hardware malfunction triggered a complete database failover to a disaster recovery site (DRS). However, not all parts of the ASX Trade system connected to the DRS database.
This was because the nature of the hardware malfunction made the failover process respond in an "unprecedented" way.
"Put simply, there was inconsistency: the broken database hardware failed-over to the backup datacentre correctly and most parts of the ASX Trade failed-over and connected to the new database. However, some parts remained and connected to the original database, thinking it was operating normally. ASX operators were initially unaware of this anomaly."
The failed hardware was replaced in time for trading to open as normal on Tuesday and ASX says that it has updated procedures to help guard against the problem reoccurring.