The effect of herding behaviour on JSE returns: A comparative analysis of before and during COVID-19

Herding behaviour has been shown to significantly influence market performance over the years, often leading to mispricing of assets due to asset bubbles. This study aimed to analyse herding behaviour on the Johannesburg Stock Exchange (JSE) before, during and after COVID-19. A cross-sectional absolute deviation (CSAD) model was used to determine the presence of herding during the specified periods, from the 1st of January 2018 to the 31st of January 2024, while causes and implications were explored further to offer a better understanding of herding behaviour. Herding behaviour was detected in all observed periods, which was not anticipated, which raised the need to discuss the policies in place to curb irrational investor behaviour. The evidence suggests that portfolio managers should understand that herding behaviour can cause market movements that are not necessarily rational or based on fundamentals. Instead, the results indicate that prices can be influenced by collective sentiment. As such, portfolio managers can assess the risks associated with blindly following the crowd and formulate strategies to avoid it. Portfolio managers can also educate their clients on the risks associated with herding behaviour to set realistic expectations and prioritise long-term stability over short-term trends. Key Words: herding behaviour; CSAD; JSE; Covid-19; South Africa