"We won't be commenting on the reasons for the termination," she told NZME. "In the interim we will be managing the securities in house," she said.
The $26.73 billion fund, the brain child of former Finance Minister Michael Cullen, was established in 2001 to invest to help smooth the cost of state-funded superannuation between today's taxpayers and future generations.
The Guardians of NZ Superannuation is charged with managing and administering the fund.
The fund operates by investing initial Government contributions - and returns generated from these investments - in New Zealand and internationally, in order to grow its size over the long term.