Public interest in buying shares in Mighty River Power is booming, with more than 90,000 people pre-registering so far.
The pre-registration process, available only to New Zealanders, launched on Tuesday morning, and there had been 92,959 sign up by 11.15pm, a spokeswoman for State-Owned Enterprises Minister Tony Ryall said.
Treasury expects that figure to top 100,000 this morning.
The strong interest caused the pre-registration website to crash briefly on Tuesday, but during the evening it was handling five registrations per second, Mr Ryall said.
"Some people may have had difficulty accessing the site, and others will have noticed it was slow in processing their requests for information," he said in a statement.
"There is plenty of time before pre-registration ends on 22 March - and there is no advantage in pre-registering earlier."
The government plans to float the state-owned energy company in April, before deciding its final share price and allocation of shares, ahead of finalising the sales in May.
New Zealanders applying for up to $2000 of shares will be guaranteed that amount, but applications above that amount could be scaled back if demand exceeds supply.
However, those who sign up early could get up to 25 per cent more shares than those who apply for shares once the offer opens.