The company accused of bringing turmoil to the electricity market with a late payment last week insists it was not at fault.
Small trader Pulse Utilities has been named as the culprit by the New Zealand Stock Exchange (NZX), which runs the electricity market.
A late payment of $667,000 on Friday triggered the collapse of payments worth $310 million - the wholesale value of one month's electricity for all of New Zealand.
Pulse says it paid its bill on time and NZX failed to process the payment.
The company also says it lodges money with NZX as security and that could have been used to prevent the entire market being brought to a halt by a single invoice.
The Electricity Commission is investigating.