In this paper we follow recent developments of panel data studies and explicitly allow for the existence of unobserved common time-specific factors where their individual responses are also allowed to be heterogeneous across cross section units. In the context of this extended panel data...

There has been a large anomaly literature where firm specific characteristics such as earnings-to-price ratio and book-to-market ratio as well as size help explain cross sectional returns. These anomalies that have been attributed to market inefficiency could be the result of a misspecification...