Testing the hypothesis that international equity market correlation increases in volatile times is a difficult exercise and misleading results have often been reported in the past because of a spurious relationship between correlation and volatility. This paper focuses on extreme correlation, that is to say the correlation between returns in either the negative or positive tail of the multivariate distribution. Using ldquo;extreme value theoryrdquo; to model the multivariate distribution tails, we derive the distribution of extreme correlation for a wide class of return distributions. Using monthly data on the five largest stock markets from 1958 to 1996, we reject the null hypothesis of multivariate normality for the negative tail, but not for the positive tail. We also find that correlation is not related to market volatility per se but to the market trend. Correlation increases in bear markets, but not in bull markets.

Benefits to portfolio diversification depend crucially on correct correlation estimates, hence it is of great importance to both risk management and portfolio optimisation that the exact nature of the correlation structure between international financial assets is understood. Recent discussion on the correlation of international equity returns has focussed on the issue of whether extreme movements in international financial markets are more highly correlated than usual returns. This implies a reduction in the benefits from portfolio diversification since extreme returns are more likely to occur with greater simultaneity. Using the Value-at-Risk methodology we are able to measure the quantile correlation structure implicit in international asset returns in a simple manner without having to resort to fully parametric modelling. We illustrate that the extraction of the quantile covariance structure from this quantile correlation structure is non-trivial. Using daily data on stock market indices for a variety of countries we observe how the correlation and covariance structure changes as we move into the tails of the return distribution. We find for extreme stock market movements the benefits to international diversification are significantly curtailed even after discarding spurious correlation changes.

How the correlation between equity returns behaves during market turmoils has been an issue of discussion in the international finance literature. Some research suggest an increase of correlation during volatile periods [Ang and Bekaert, 2002], while others argue its stability [Forbes and Rigobon, 2002]. In this paper, we study the impact of returns and volatility on correlation between international equity markets. Our objective is to determine if there is any asymmetry in correlation and identify the main explanation for this asymmetry. Within a framework of autoregressive models we quantify the relationship between return, volatility, and correlation using the generalized impulse response function and we test for the asymmetries in the return-correlation and volatility-correlation relationships. We also examine the implications of these asymmetric effects for the optimal international portfolio. Empirical evidence using weekly data on US, Canada, UK, and France equity indices, show that without taking into account the effect of return, there is an asymmetric impact of volatility on correlation. The volatility seems to have more impact on correlation during market upturn periods than during downturn periods. However, once we introduce the effect of return, the asymmetric impact of volatility on correlation disappears. These observations suggest that, the relation between volatility and correlation is an association rather than a causality. The strong increase in the correlation is driven by the market direction and the level of return rather than the level of the volatility. These results are confirmed using some tests of the asymmetry in volatility-correlation and return-correlation relationships in separate models and then in a joint model. Finally, we find that taking into account the asymmetric effect of return on correlation leads to an average financial gain ranged between 3.35 and 37.25 basis points for optimal international diversification.

The co-movement of international equity markets in different return environments is examined using estimates of realized correlation and volatility. Using a simple ordinary least squares (OLS) regression framework, correlations are shown to be similarly elevated in periods characterized by extreme returns in both up and down markets, which contradicts a body of extant research that finds correlations increase in down markets but not in up markets. In contrast, volatility is much greater in down markets than in up markets. This suggests that it is not a lack of diversification that matters for comparative performance in bear markets, but rather the relative magnitude of negative returns typically experienced during such periods.

The interrelationship between international stock markets is becoming a key issue in international portfolio managment and risk measurement. The dynamics of security returns and their risk characteristics have a crucial role in the financial market's therory. Recent empirical studies have tested market efficiency measuring the degree of integration of international financial markets. These studies have shown that international markets react quickly to news but they are volatile and difficult to predict and with a changing correlation structure of security returns among countries.In this paper we analyze the nature of the relationship between the major international stock markets in Canada, Japan, U.K. and the U.S., using the common trends and common cycles approach. We investigate the presence of co-movements trying to detect a long-term stationary component, the common trend, and a short term stationary cyclical component, among international stock markets. The implications on international portfolio management are alos discussed.