International Diversification with Factor Funds
提出利用因子基金（规模、账面市值比、动量因子）增强国际分散化投资组合的效率，基于10个发达国家1981-2008年数据，发现加入本地因子基金能显著提高夏普比率，其中账面市值比因子贡献最大。
We propose a new investment strategy employing “factor funds” to systematically enhance the mean-variance efficiency of international diversification. Our approach is motivated by the increasing evidence that size (SMB), book-to-market (HML), and momentum (MOM) factors, along with the market factor, adequately describe international stock returns, and by the direct link between investors' portfolio choice problems and international asset pricing theories and tests. Using data from 10 developed countries during the period 1981–2008, we show that the “augmented” optimal portfolio involving local factor funds substantially outperforms the “benchmark” optimal portfolio comprising country market indices only as measured by their portfolio Sharpe ratios. This strongly rejects the intersection hypothesis which posits that the local factor funds do not span investment opportunities beyond what country market indices do. Among the three classes of factor funds, HML funds contribute most to the efficiency gains. In addition, the local version of factor funds outperforms the global factor funds. The added gains from local factor diversification are significant for both in-sample and out-of-sample periods, and for a realistic range of additional investment costs for factor funds, and remain robust over time.