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....

Roll [1988] observes low R2 statistics for common asset pricing models due to vigorous firm-specific return variation not associated with public information. He concludes that this implies “either private information or else occasional frenzy unrelated to concrete information” [p. 56]. We...