While broad support from money managers is nice, the backing of Japan's biggest pension fund for new investor guidelines is the reason they will succeed, according to Fidelity Worldwide Investment.

Almost 130 institutions have adopted the stewardship code, the Financial Services Agency said June 10. They are estimated to own more than $860 billion in Japanese stocks, about one-fifth of all shares.

For Hiroki Sampei, director of research at Fidelity Worldwide Investment in Tokyo, the Government Pension Investment Fund's enthusiasm bodes well for the principles' success. GPIF, with ¥22.1 trillion in Japanese equities, signed up for the code in May.