Investigations are underway into the non-payment last week of a $700,000 bill within the electricity industry that threw the market into disarray.
The alleged breach happened on the day that a month of electricity trades worth $300 million is supposed to be settled and caused a cascade of other failures.
Though subsequently settled, it led to Mighty River Power, Genesis Energy and Contact Energy lodging a complaint with the Electricity Commission against the New Zealand Stock Exchange (NZX), which operates the electricity market.
NZX, in turn, accused small firm Pulse Utilities of a breach. However, Pulse says it did pay one hour ahead of the deadline and that it has banking documents to prove it.
Electricity Commission chair David Caygill says the payments were made on Monday morning and there is no reason to be concerned about the integrity of the settlement system.