We explore the link between stock returns and changes in market capital concentration across firms. Our theory uncovers a concentration risk factor driven by time-varying changes in the distribution of market capital. A powerful implication of our theory is the necessary existence of this...

We uncover a large and significant low-minus-high rank effect for commodities across two centuries. There is nothing anomalous about this anomaly, nor is it clear how it can be arbitraged away. Using nonparametric econometric methods, we demonstrate that such a rank effect is a necessary...