Abstract
In this study, the sectoral effects of partial lockdown dated 13.04.2021 and full lockdown dated 26.04.2021, which were taken in Turkey during the COVID-19 epidemic process, on the BIST market were tried to be determined. In the study, in which the Event Study method was used, the efficiency of the stock market and whether sector-based abnormal returns could be obtained from this market was measured. In the analysis, it was seen that the partial lockdown decisions taken during the COVID-19 pandemic process had a negative effect on the selected markets within the BIST. In addition, it was concluded that the decision of full lockdown had a positive effect on the markets, and it was seen that the market was not efficient in the semi-strong form.