An investor has complained to the authorities about Refining NZ's slowness to tell the market about the pipeline leak which has led to travel disruption amid a shortage in aviation fuel.
Refining NZ found the leak last Thursday but only made an announcement to the sharemarket at 8.30am this morning.
Peter Wakeman, who owns shares in Auckland Airport, said he was concerned people were trading shares last week without full knowledge about the potential impact on the company and other listed companies such as the airport and airlines.
"It is unbelievable for Refining NZ to not make the disclosure until Monday morning."
Wakeman said he had complained to the NZX and the Financial Markets Authority about the delay.
Stock exchange operator NZX has said it is in talks with Refining NZ regarding its announcement about the pipeline leak.
Listed companies have an obligation to continuously report anything that may have a material impact on them.
Asked if the NZX was looking into the timing of the announcement a spokeswoman said it was "engaging with Refining NZ on this morning's announcement regarding the Wiri pipeline leak".
"NZX is unable to provide any further comment at this time."
The Herald has asked Refining NZ why it did not inform the market of the leak before this morning but has yet to receive a response.
The company has said the leak will affect revenue by $10 million to $15 million.
Refining NZ generated annual revenue of $353.8 million in calendar year 2016.
Its shares have fallen 3 per cent or 8c to $2.40 in early trading.
Meanwhile Auckland Airport shares have risen 9c to $6.40 while Air New Zealand's shares have fallen 7c to $3.18.