FuturePlus chief investment officer Terry Newson has resigned after nearly two years in the job.
Newson began with the fund in December 2005 and was also responsible for the investments of Local Government Superannuation Scheme and the Energy Industry Superannuation Scheme.
His previous job was as chief executive of the Stevedoring Employees Retirement Fund (SERF).
In June 2006, SERF and the Seafarers Retirement Fund awarded FuturePlus a $2.2 billion investment mandate.
Overall FuturePlus manages more than $14 billion in funds under management.
Newson also served as chair with the Fund Executives Association Limited.
"The board will be meeting to discuss his replacement," a company statement said.