TOKYO -- Currency traders are watching as Japan's Government Pension Investment Fund -- one of the world's biggest institutional investors -- is expected to increase its weighting in foreign bonds in a potentially market-moving portfolio review set for as early as this month. Such a change to the 160 trillion yen ($1.5 trillion) pension fund's asset mix could serve to limit the yen's gains at time when the coronavirus outbreak is stirring up volatility in financial markets.