Why Not Diversify Internationally Rather Than Domestically?
研究发现，由于投资组合总风险不仅随证券数量增加而降低，还随证券间独立程度提高而降低，因此将投资组合分散到国内外普通股能显著降低风险。
Because total risk for a portfolio declines not only with the number of securities included but with the degree of independence among these securities, substantial risk reduction results from diversifying a portfolio across foreign as well as domestic common stocks.