The week-of-the-month effect in stock returns: The evidence from the S&P Composite Index

Theweekend effect and theyearend effect are some of the seasonal anomalies in financial markets that have been widely discussed in the finance literature. In this paper, using weekly observations of the S&P Composite Index over the period from July 1962 through June 1990, plus several subperiods, the authors identify the presence of a thus far unknown seasonal anomaly in the form of aweek-of-the-month return pattern in the stock market. The results suggest the existence of a statistically different weekly return pattern for different weeks of a month. Specifically, the returns during the first week of a month tend to be significantly positive while the returns during the other weeks of a month are statistically indistinguishable from zero.