International diversification of investment portfolios: U.S. and Japanese perspectives

In this paper, the authors analyze the gains from international diversification of investment portfolios from the Japanese as well as the U.S. perspectives. The major findings of this paper include: First, the ‘potential’ gains from international, as opposed to purely domestic, diversification are much greater for U.S. investors than for Japanese investors. For U.S. investors, the gains accrue not so much in terms of lower risk as in terms of higher return, and the opposite holds for Japanese investors. Second, using various ‘ex ante’ international investment strategies designed to control parameter uncertainty, U.S. investors can realize substantial gains from international diversification in out-of-sample periods. Japanese investors, however, can gain relatively little. Third, hedging exchange risk generally allows the U.S., but not Japanese, investors to benefit more from international diversification. For U.S. investors, the international bond diversification with exchange risk hedging offers a superior risk-return trade-off than the international stock diversification, with or without hedging.