| Abstract: | We report on a seasonal pattern that has persisted in the Japanese stock market for more than half a century: Mean stock returns are significantly positive for months during the first half of the calendar year and significantly negative for months during the second half. Dubbed the Dekansho‐bushi effect, this seasonality is independent of other known calendar anomalies, such as the so‐called January effect. The Dekansho‐bushi effect should be distinguished from the ‘sell in May effect,’ because Japanese stocks perform well in June and poorly in November and December. The Dekansho‐bushi effect varies in magnitude among firms and is particularly significant among small firms with high book‐to‐market ratios. Nonetheless, the effect exists, regardless of a company's size or book‐to‐market ratio. |
