Mr Phelps will remain in the position until Investa has found a suitable replacement.
IOF chair Deborah Page said Mr Phelps managed the fund during a period of significant transformation, including the disposal of $400 million in offshore assets and the acquisition of over $1.1 billion of high quality Australian assets.
“Tony leaves IOF in a very strong position and we thank him for his service and expertise during this important part of the fund’s history,” said Ms Page.
Mr Phelps said the decision to leave Investa had been difficult.
“I am very confident in the future of IOF and the capability of the Investa platform and management team, and I look forward to watching IOF’s continued success,” he said.