Do expected asset returns vary through time? Why do some assets exhibit higher average returns than others? How can factors that drive expected returns in the time series be linked to factors that explain the cross-sectional dispersion in average returns? How do these findings affect...

This paper studies some seemingly anomalous results that arise in possibly misspecified and unidentified linear asset-pricing models estimated by maximum likelihood and one-step generalized method of moments (GMM). Strikingly, when useless factors (that is, factors that are independent of the...