Overreaction after Controlling for Size and Book-to-Market Effects and its Mimicking Portfolio in Japan

In this paper we observe that firm size (SZ) and book-to-market (BM) cannot fully explain stock returns on prior-return- (PR-) based portfolios in the Japanese stock market. The overreaction effect after controlling for the SZ and BM effects is significant and persistent, and accounts for a large part of the zero-investment returns on the loser to the winner. We therefore propose a new mimicking portfolio whose returns mimic the common factor in returns related to overreaction. Our evidence shows that the proposed four-factor model captures common variation in returns on portfolios, based on stocks’ SZ, BM, and PR, better than the well-known three-factor model does. Copyright Springer Science + Business Media, Inc. 2005