The Indian stock market is volatile and sensitive to various effects like holiday effect, month effect and day-of-theweek effect. The paper aims at analyzing the day-of-the-week effect in the stock returns of the National Stock Exchange. The paper exhibits descriptive research based on secondary data. The average stock returns of 50 securities at the S&P CNX Nifty are analyzed for each day of the week individually and overall day effect taking the financial year 2013-14. Z-test is used to study the difference between the individual mean day returns on all the trading days making associations as Monday & Tuesday, Monday & Wednesday, Monday & Thursday and so on. The null hypothesis that the mean returns are equal for all trading days was true at 5% level of significance as well as 1% level of significance. The hypothesis was tested making 10 combinations of different pairs across the trading days. The null hypothesis was accepted in all the 10 cases at 5% and 1% significance level. The research offers significant implication for investors and analysts by stating the updated risk and return analysis of the securities listed at the National Stock Exchange. The specific findings are related to S&P CNX Nifty Index securities return. The research may be carried forward for diverse indices and stock exchanges across the country and analytical comparisons may be done.