Anomalies in US equity markets: a re-examination of the January effect

This study investigates the January effect in US equity markets using three market indexes from 1964-1998: Dow Jones Composite, NYSE Composite and the SP500. Chow tests for structural stability indicate that the estimated parameters in an equation testing for monthly seasonal effects in the stock market are not stable over time. In the 1964-1987 sample period it is found that January returns are positive and significant in all three stock market indexes. After 1987, January returns are positive but not statistically different from zero. The results therefore provide no statistical support for the January effect in US equity markets in the post-1987 market crash period.