The Oregon Investment Council has announced a $400 million investment in Global Infrastructure Partners Fund III in an attempt to diversify its investment strategy and increase returns for the Oregon Public Employees Retirement Fund (OPERF).

The new investment, which is contingent on negotiation and legal approval, is to "improve the fund's sustainability and better moderate volatility over time," said State Treasurer Ted Wheeler, one of six investment council members.

The Oregon Investment Council is boosting investment in "alternatives" as part of this strategy.

OPERF operates on an assumed 7.5 percent return rate. The fund posted a 7.3 percent return for 2014.

GIP aims to raise as much as US$15 billion for the fund. GIP's is a global leading investor in, and operator of energy, transport and water/waste infrastructure assets.

Washington State Investment is planning invest US$ 500 million in the fund and other US$500 million in a separate account, on which the company would have investment discretion.