The New Zealand Superannuation Fund has had one of its best years yet, helped by strong growth in global sharemarkets.
The long-term state pension fund made a 20.7 percent return on its investments, adding $5 billion to the fund in the year ended in June, after paying record taxes of $1.2b.
The fund was $35bn dollars as of 30 June. It has enjoyed an average return of 10.2 percent a year over the past 14 years.
Fund chair Catherine Savage said the fund was generating world-class returns and creating significant wealth for New Zealanders on a sustained basis.
"It should not, however, be measured on its short-term returns," she said.
"We are here to create long-term value for New Zealand taxpayers."
Fund chief executive Adrian Orr said the risk to the fund had been reduced over the past year as global markets continued to rally, but there was still reason for caution.
"The returns we have been achieving are above our long run expectations, and we are cautious about the outlook," Mr Orr said.