Industry returns cannot be explained fully by well-known asset pricing models. This study reveals that common factors extracted from industry returns carry significant risk premiums that go beyond the explanatory power of size, book-to-market (BM) ratios, and momentum. In particular, this study shows that (1) the small-firm effect is significant only for firms whose market capitalization is below their industry average; (2) the BM effect is an intra-industry phenomenon; (3) a one-year momentum effect is significant only for firms whose BM ratio is smaller than the industry average and limited to non-January months; and (4) there is seasonality in all effects that cannot be explained by risk-based asset-pricing models. Neither rational nor behavioral theories alone can explain industry returns, and it is perhaps too hasty to attribute asset pricing anomalies to a single driving force.

We establish a significant and robust connection between asset growth (AG) and style investing by showing that past style returns constructed based on AG and size jointly predict future stock returns significantly. Motivated by this notion, we propose a style momentum strategy based on AG and size and find that it dominates price momentum and size-BM style momentum in generating momentum profits. We examine two explanations for this predictability, including risk exposure to common risk factors and the limited-attention theory. Empirical evidence shows that the AG-size style momentum profit is induced because investors neglect the AG-size style performance, consistent with the limited-attention explanation, but not risk exposure to the investment factor. Further, we show that the profit of the AG-size style momentum is robust to different time periods partitioned by several time-series predictors.