Japan's public pension fund, the world's largest, logged more than $50 billion in investment losses last fiscal year as the yen surged and Tokyo stocks fell amid global market turmoil, a person with direct knowledge of the matter said.

Portfolio losses for the Government Pension Investment Fund for the 12 months through March were between 5 trillion and 5.5 trillion yen, the person told Reuters on Friday, speaking on condition of anonymity as the results are not public.