Testing Weak Form of Efficient Market Hypothesis Before and During COVID-19 Pandemic Periods: Evidence From Indonesia

Abstract

This research examines the Weak Form of Efficient Market Hypothesis (WFEMH) on the Indonesian Stock Exchange. Specifically, the study empirically tests the extent to which future stock price changes are not determined by the previous period's stock price movement or the stock price changes are random. Thus, future stock price changes fully reflect new relevant information on the market. This research utilizes the daily closing price of the Composite Stock Price Index on the Indonesian Stock Exchange from 2011 to 2021. The sample of the study is divided into two groups. The first group is from January 2011 to December 2019 as the normal pre-COVID-19 period, and the second group is from January 2020 to December 2021 as the economic crisis period (during COVID-19). We apply three statistical tests: a unit root test, serial correlation test, and regression model examining the WFEMH. The study found that the WFEMH is documented in the Indonesian Stock Exchange in some periods before and during COVID-19. These research findings advocate that regulators and policy-makers should monitor the issue of the market efficiency of public firms in Indonesia.