The coronavirus pandemic, which resulted in the world’s biggest lockdown resulted slowest global financial crisis and led to fall in stock markets. India too witnessed sharp fluctuation in the financial markets during initial days of lockdown. In this background, the current paper aims to examine the presence of seasonal anomalies like week day effect and semi-monthly effect on the stock returns of Nifty 50 and Nifty 500, major stock indices of National Stock Exchange, India in the COVID period between February 2020 and October 2020. The daily log returns for both the indices are calculated and observational study was carried out employing descriptive statistics, Kruskal-Wallis H-test, Mann-Whitney U test, unit root test, cross correlation, and regression analysis. In order to investigate the existence of stationarity, unit root tests like ADF test in addition to the PP test have been applied. Though, the COVID-19 period was indeed marked by sharp volatility, yet the absence of calendar anomalies like the week day effect and semi-monthly effects in Nifty 50 and Nifty 500 is quite significant. This resonates with the broader trend observed in global markets where such irregularities are fading, possibly due to increased market efficiency, algorithmic trading, and the rapid dissemination of information.