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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.

This research investigates how the overall mood of investors influences the profits of the major commercial banks traded on the JSE. Although behavioural factors are increasingly acknowledged in financial markets, there is very little empirical evidence that investor sentiment has any impact on the South African banking sector, despite this sector being the main driver of financial stability and economic growth. This study investigated whether investor sentiment has a significant impact on bank stock returns in both the short and long term. The research period ranged from September 2008 to March 2025 and used monthly return data. The paper implements the Autoregressive Distributed Lag (ARDL) approach to illustrate immediate and long-term relationships between sentiment, macroeconomic variables, and bank performance. The findings demonstrate that investor sentiment is one of the significant factors influencing bank stock returns, but the effect varies between different banks. Sentiment, on average, tends to have a negative effect on the majority of banks in the long run, which means that in times of extreme optimistimism  are followed by those of overvaluation and subsequent correction. However, one bank revealed a positive return-sentiment relationship which suggests that characteristics unique to a specific bank can have a moderating effect on behavioural factors. The short-run outcomes indicate that bank stock returns are very reactive to changes in sentiment and macroeconomic shocks and at the same time, diagnostic tests for model reliability support these results. The paper contributes to behavioural finance literature by delivering fresh data derived from an emerging market and providing an answer to the problem of bank-level disaggregated analysis that has been neglected. In addition to the theoretical contributions, the results can be turned into actionable insights by investors, policymakers, and portfolio managers who will be reminded of the importance of including sentiment indicators in their bank performance assessment and risk management activities in the South African financial sector.

The Johannesburg Stock Exchange (JSE) is considered a cornerstone of the South African economy, with its size-based indices serving as critical benchmarks for passive investment and portfolio construction. Although macroeconomic variables affect stock returns, the existing literature has primarily relied on linear models which yield heterogeneous results and do not allow for the dynamic and changing structure of financial markets. Consequently, this study investigates the nonlinear, regime-dependent effects of key macroeconomic variables such as inflation, money supply, short- and long-term interest rates, GDP, and the real effective exchange rate (REER) on the returns of the JSE Fledgling, Small-Cap, and Mid-Cap indices. Utilizing monthly data from 2002 to 2024, the study employs a two-state Markov Regime-Switching which allows the study to endogenously address the changes in bull and bear market regimes. The most pressing finding is that the Real Effective Exchange Rate (REER) is a consistently positive driver of returns across all market conditions, while the influences of other variables, such as interest rates and GDP growth, are highly dependent on the market regime (bull or bear) and the specific index size. Finally, these findings lead us to conclude that the relationship between macroeconomic fundamentals and stock returns is not a constant phenomenon but rather is fundamentally dependent on the regime, lending strong support for the Adaptive Market Hypothesis. This insight is significant for investors and portfolio managers, underscoring the necessity of adaptive, regime-sensitive strategies for effective risk management and portfolio allocation on the JSE.

The Adaptive Market Hypothesis (AMH) allows for a re-evaluation of the relationship between macroeconomic variables and stock market returns, acknowledging that this relationship is time-varying and asymmetrical. This study investigates the impact of macroeconomic factors on the Johannesburg Stock Exchange (JSE) sector returns under varying market conditions from January 2008 to December 2024. Using a Markov regime-switching model, the findings show that macroeconomic effects on sectoral returns are regime-dependent and time-sensitive. In bullish markets, inflation growth has a significant negative impact on Industrial sector returns, but no significant effect during bearish regimes. For the Financial sector, inflation and money supply growth negatively affect returns, while the real effective exchange rate growth has a positive impact. In the Resource sector, all macroeconomic variables significantly influence returns during bearish conditions, with inflation growth showing a notable negative effect. Overall, JSE sector returns exhibit bull and bear market dynamics, and the influence of macroeconomic variables is neither uniform nor static aligning with the AMH framework.