We test the efficient market hypothesis by using machine learning to forecast future stock returns from historical performance. These forecasts strongly predict the cross section of future stock returns. The predictive power holds in most subperiods, is strong among the largest 500 stocks, and...

This monograph consists of two parts. One part is portfolio selection theory and the other part is capital asset pricing theory. For each part, a comprehensive review of the original theory, efforts to improve the theory afterwards and future works to be done are presented. Some innovative...