We document a robust cross‐sectional positive association across industries between a measure of the economic efficiency of corporate investment and the magnitude of firm‐specific variation in stock returns. This finding is interesting for two reasons, neither of which is a priori obvious. First, it adds further support to the view that firm‐specific return variation gauges the extent to which information about the firm is quickly and accurately reflected in share prices. Second, it can be interpreted as evidence that more informative stock prices facilitate more efficient corporate investment.

This paper compares the comovement of individual stock returns across emerging markets. Campbell et al. and Morck et al. have shown that the United States saw rising firm-specific stock return variations, and thus declining comovement, over the second half of the twentieth century. We detect a similar, albeit weaker, pattern in most, but not all, emerging markets. We further find that higher firm-specific variation is associated with greater capital market openness, but not goods market openness. Moreover, this relationship is magnified by institutional integrity (good government). Goods market openness is associated with higher marketwide variation.