Overreaction Effects Independent of Risk and Characteristics : Evidence from the Japanese Stock Market

This paper shows that the firm size (SZ) and the book-to-market ratio (BM) cannot fully explain stock returns on prior-return-based portfolios in Japan. The overreaction effect after controlling for SZ and BM effects is significant and plays an important role in explaining the zero-investment returns on the loser-to-winner strategy. Motivated by this observation, we construct a portfolio whose return serves as a new factor that mimics overreaction. This new factor improves the performances of the three-factor model [Fama and French (1993)] in several prior-return-based and characteristics-based portfolios