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, E.F., French, K.R., 1993. Common Risk Factors in The Returns on Stocks and Bonds. Journal of Financial Economics. 33, 3-56] in several prior-return-based and characteristics-based portfolios.