Trading resumed at 1pm.
It's the fourth day in a row that trading has been disrupted by the attacks.
Finance Minister Grant Robertson said the government is aware of the impact the cyber attacks have been having on the stock market and is treating the issue very seriously.
He said although NZX is a private company, however it is important the government works with private companies like them when they experience issues such as the cyber attacks.
The Government Communications Security Bureau is involved in trying to counter the attacks.
The national security system has been activated to ensure coordination between agencies to support NZX with the cyber attacks, Robertson said.
Robertson said he was limited in what he could say about the behind-the-scenes action the government was taking due to security considerations.
One overseas report says the NZX has been the worst affected among a group of financial service providers subject to the same type of attack around the world in the past couple of weeks.
Among those hit have been online payments company PayPal.
Earlier, it said it would open as normal today after beefing up its IT systems to counter cyber attacks.
The NZX has had to cut trading short over the past three days because its systems have been by an offshore cyber attack.
It managed only one hour's trading yesterday after it could not publish company announcements.
The NZX says it has been working with its network service provider, Spark, and cyber security experts, including the Government Communications Security Bureau to counter the attacks.
Financial adviser at Hobson Wealth Partners Brad Gordon told Morning Report that the crashes have caused significant inconvenience and have come in the middle of a significant reporting period.
He said having the exchange close abruptly puts New Zealand traders at the whim of the overseas market when the market next opens.
Gordon said market participants expect to be able to trade throughout the day.
"There's a lot of algorithmic trading that happens, say volume weight prices that happens throughout the day, which means those orders will be hanging over a night."
He said clients are frustrated.
"There were a number of orders weren't able to be done yesterday, and obviously it just leaves them just a little bit uncomfortable, particularly having to sit on positions overnight that they were expecting to be able to trade."
Gordon said there is a question about why it has been happening to NZX technology infrastructure when it is not happening to other stock exchanges.
