The man who helped name the world's biggest pension pool is back as one of its money managers, and says the fund's new approach to buying stocks will rub off on other retirement investors.

Under pressure to achieve higher returns, the ¥126.6 trillion Government Pension Investment Fund changed how it buys Japanese shares in April, adding more foreign and lesser-known firms as external managers. It chose U.S.-based Dimensional Fund Advisors LP as one of three companies for smart-beta strategies, broad investment using weightings other than market value.

The equity revamp "shows how much GPIF has evolved," John Alkire, Dimensional's Japan head, said in an interview in Tokyo on July 8. His company oversaw $378 billion as of June 30. "GPIF tends to be the bell cow. The sweeping change occurring at the fund is almost like a wake-up call for corporate pensions. They're thinking that there's maybe more risk in not owning Japanese equities."