New Zealand Superannuation Fund, Auckland, terminated GMO from three equity mandates, according to the NZ$16.6 billion (US$11.8 billion) fund's website.
GMO's original mandates were NZ$140 million in global equities, NZ$114 million in non-U.S. small-cap equities and up to NZ$500 million in multistrategy equities.
The terminations do not affect the fund's strategic asset allocation, according to a news release. GMO Renewable Resources will continue to run a timber mandate for the fund.
Fund spokesman Paul Gregory declined to provide additional information in an e-mail response to questions.
Separately, Tore Hayward, the fund's head of strategy, resigned to take a similar position at the NZ$10 billion Accident Compensation Commission fund, Wellington.
Neil Williams, New Zealand Super's head of public markets, was named interim head of strategy. A fund spokesman declined to comment on a whether a permanent replacement would be sought.
David Chaplin, a reporter with Investment magazine in Sydney, contributed to this story.