An NZX incident report pins last Thursday's outage on a "human and process control error".
In short, someone restarted the exchange's trading platform by mistake - and the final couple of hours of the trading day were lost as an overseas support call was required to mop up after the glitch.
An "NZX operator was completing a task that involved restarting a non-production version of Nasdaq ME but had logged into production in error," the report said.