To diversify or not to diversify internationally?

•Neither industry nor country correlations exhibit a long-term positive trend.•Industry and country correlations jump during recessions.•These correlations tend to revert in stable periods.•Diversifying across industries rather than countries is more efficient.•Diversifying across emerging markets rather than developed markets is more efficient. Using alternative measures of return correlations, we show that neither industry nor country correlations exhibit an ever-increasing trend. Instead, correlations jump during recessions with a tendency to revert in stable periods. This keeps international diversification still important despite the financial integration that might have increased correlations permanently. Moreover, the mean of industry correlations is statistically lower than that of country correlations, suggesting that cross-industry diversification is more efficient. Finally, diversifying through industries of emerging markets rather than those of developed markets reduces mean correlations more. These results are robust to several correlation definitions.