Some evidence on the gains from international diversification for Canadian investors

It is easily demonstrated ex post that international portfolio diversification results in increased returns and reduced risk. However, to determine the value of international diversification as an effective portfolio management strategy, it is necessary to form portfolios based on information available at the time of their composition, and then evaluate the performance of the portfolio in the following months. This is the main focus of our study, which adds several innovations to past research. First, we use daily rates of return on 23 national indices to evaluate the value of international diversification for a Canadian investor. Second, we evaluate the predictive value of the historical variance-covariance matrix vis-à-vis alternative models. Third, we use the Bayes-Stein correction to reduce errors in the historical return vector. Finally, we use a quadratic programming model in order to introduce the effects of constraints on the optimisation process. The results, obtained over the 1986–1989 period, are not in favour of international diversification. Returns on diversified portfolios were often lower than returns on the low-risk Canada market during the low-performance portfolio test periods. In other cases, higher returns on diversified portfolios could not be justified by their higher volatility. It is possible that these results may be partially due to the effects of the market crash in October 1987. Nevertheless, our study brings up many directions for future research. Is international diversification in fact profitable? Is portfolio optimisation appropriate in an international context? Finally, what is the best way to estimate the expected return vector in various markets?