Global equity investing: The benefits of diversification and sizing your allocation
■ Regardless of where they live, investors have a significant opportunity to diversify their equity portfolios by investing outside their home market. Despite this opportunity, investors on average have maintained allocations to their home country that have been significantly larger than the country’s market-capitalization weight in a globally diversified equity index.
■ In each market we examined, our analysis indicated that volatility was reduced most with an allocation to international equities of between 40% and 50%. While this observation may help investors determine the appropriate mix of domestic and international equities, volatility reduction is not the only factor to consider.
■ This paper concludes that although no one answer fits all investors, global market-capitalization weight serves as a helpful starting point in determining the appropriate allocation between domestic and international equities. In practice, many investors will consider an allocation to international equities well below global market-capitalization weight based on their sensitivity to a number of considerations, including volatility reduction, implementation costs, taxes, regulation, and their own preferences.
Full pdf @ https://www.vanguard.com/pdf/ISGGEB.pdf