The fund will be accepting commitments until Jan. 31.
The fund exceeded its $400 million target and closed above its initial $500 million hard cap.
The plan had previously posted the position to the National Association of Retirement Plan Administrators website in April.
The fund will provide senior secured debt capital to middle market North American businesses.
The city will award a contract by Oct. 15.
The commitment represents a new relationship for the plan.
The county’s new investment manager will replace incumbent Sterling Capital Management.
The city is seeking a firm to establish and oversee a Section 115 trust.
The board was notified of two recent equity manager terminations and a new private equity commitment.
The deal is expected to close later this year and will see HighVista Strategies gain approximately $4 billion in assets under management.