Stock Market Seasonality in an Emerging Market
Authors: Sarma S N 
Published: August 2016

The objective of this paper is to explore the day-of-the-week effect on the Indian stock market returns in the post-reform era. Till the late seventies, empirical studies provided ample evidence as to the informational efficiency of the capital markets advocating futility of information in consistently generating abnormal returns. However, later studies identified certain anomalies in the efficient market postulate. One major anomaly brought forth was the calendar-related abnormal rates of return. Various studies in this domain empirically demonstrated, through parametric and non-parametric tests on the stock returns data, that turn of the year, month, week, and holidays have consistently generated abnormal equity returns in both the developed and emerging markets unrelated to the attendant risks. Studies on the Indian stock markets' calendar anomalies, especially in the post-reform era, are very few. In an attempt to fill this gap, this study explores the Indian stock market's efficiency in the 'weak form' in the context of calendar anomalies, especially in respect of the weekend effect.

Daily returns generated by the SENSEX, NATEX, and BSE200 during January 1st 1996 to August 10th 2002 comprising a total of 1,667 observations for each of the indices are considered for testing the seasonality. While most of the studies have considered the returns of one of the major indices based on the closing values, this study examines the multiple indices for possible seasonality. An analysis of returns' pattern of multiple indices is helpful in identifying the presence or otherwise of the stock market seasonality associated with various portfolios and for testing the efficacy of investment game based on the observed patterns of the returns. This study employed the daily mean index value for generating the daily returns to relax the implied assumption of the earlier studies — by considering the closing values of the indices — that trading is done at the closing values. A non-parametric test — Kruskall-Wallis test using 'H' statistic — is employed for testing the seasonality in the Indian stock market returns. The null hypothesis tested is that there are no differences in the mean daily returns across the weekdays.

The major findings of the study are as follows: The Indian stock markets do manifest seasonality in their returns' pattern. The Monday-Tuesday, Monday-Friday, and Wednesday-Friday sets have positive deviations for all the indices. The Monday-Friday set for all the indices has the highest positive deviation thereby indicating the presence of opportunity to make consistent abnormal returns through a trading strategy of buying on Mondays and selling on Fridays. The above-mentioned active strategy is found to be beneficial in case of SENSEX The above-mentioned active strategy is found to be beneficial in case of SENSEX alone during the study period while for the others — NATEX and BSE200 — a passive ‘buy and hold’ strategy is more effective.

The study concludes that the observed patterns are useful in timing the deals thereby exploring the opportunity of exploiting the observed regularities in the Indian stock market returns.