Oklahoma Public Employees Retireent System, Oklahoma City, will issue an RFP for an enhanced index equity manager with a benchmark of the S&P 500 in August. The search is a result of the $4.8 billion funds asset allocation study. Finalists for the $250 million portfolio probably will be selected in October with a hire in November, said Stephen Edmonds, executive director. The funding is likely to come from an existing equity index portfolio. A final selection in the search for small-cap value equity and international equity managers also is expected at the October meeting.