Abnormal returns have been found on days near the turn of the calendar months. Previous studies have linked the phenomenon to month-end paychecks, of which a sizable proportion goes into employees’ retirement accounts and is then automatically invested in the market. Since many institutions adopt a semi-monthly pay schedule, we test the hypothesis that the market should exhibit detectable mid-month abnormal movement. Our results indicate that the 16th day of the month statistically and economically outperforms all other calendar days except the 1st and 2nd. As more and more institutions transition into bi-weekly pay schedule, however, the mid-month payday anomaly becomes less prominent.

Keywords: Abnormal Return, Anomaly, Payday, Mid-Month, Market Efficiency

Continue reading here.