EFFICIENT MARKET HYPOTHESIS DURING COVID-19 PANDEMIC: BRICS-T COUNTRIES

The impact of COVID-19 on financial markets has become a significant topic of research in the literature. Particularly, the declaration of the outbreak as a global pandemic by the World Health Organization on March 11, 2020, altered investors' risk perceptions and led to major fluctuations in stock markets. In this study, the response of stock indices in BRICS-T countries (Brazil, Russia, India, China, South Africa, and Türkiye) to the pandemic declaration was analyzed using the Event Study method. The event window was set as -5 to +5 days, and the estimation window was selected as the 90 days preceding the event. As a result of the analysis based on the comparison of normal and abnormal returns, it was found that all BRICS-T stock markets, except China, were not semi-strong form efficient. In addition, the results of the paired sample t-test applied to all stock markets demonstrated that the difference between abnormal returns calculated before and after COVID-19 was statistically significant. In this context, it was concluded that, unlike previous outbreaks, the COVID-19 pandemic led to significant fluctuations in financial markets. This study provides an important contribution to understanding the effects of the pandemic on emerging markets and examining investor behavior.