Here's what caused the ASX outage on Monday

Photo: Ryan Pierse/ Getty Images.

An initial investigation into the cause of the major outage at the ASX on Monday has found the failure was caused by hardware supporting the database behind trading.

The exchange maintains a series of redundant systems, so that if one fails, another takes over.

However, in this case, parts of the system thought that the broken hardware was still operational and kept trying to re-connect.

The start of trading was delayed and Australian shares only traded for a short time Monday before the system went down again.

An eight-page report on the ASX’s investigation released today didn’t name the piece of faulty hardware.

Local traders, who couldn’t complete trades for clients, were unimpressed.

Dominic Stevens, the managing director and CEO of the ASX, today apologised again, saying the outage was unacceptable.

“I again offer my apologies for the disruption caused,” he days

“Monday’s disruption was especially disappointing because of ASX’s long and proud record of system reliability.

“In seven of the last 10 years, ASX’s equity trading platform has recorded 100% system uptime. The remaining three years recorded over 99.7% each. Over the same period, there has been an almost tenfold increase in the average number of trades processed each day. Our other trading, clearing and settlement systems have demonstrated similar reliability over the years.”

The faulty hardware was replaced Monday evening and the ASX has been operational ever since.

“Our customers, regulators and many other stakeholders quite rightly expect reliability and availability around the clock, every day,” says Stevens. “ASX does too.

“ASX does not decide to close the market lightly. Understandably, concerns have been raised on various fronts. However, we make no apologies for following our long-established and well understood protocols nor for exercising our judgement to ensure the market was fair, orderly and transparent. That is ASX’s responsibility.

“I am determined that in understanding what happened on Monday we will emerge stronger and better able to manage the market’s myriad challenges. We are directing our efforts to ensure there is no recurrence and listening to what our customers say about improving the way we communicate with them. And of course, we are also cooperating closely with ASIC to help with its review.”

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