Purpose: This study examines the relationships between herding behaviour, market overreaction and financial stability in developed and Brazil, Russia, India and China (BRICS) markets from 1 January 2017 to 31 December 2023. It identifies the significant differences in these phenomena across different market types and their implications for financial stability.Design/methodology/approach: This study employs panel data regression, quantile regression, Granger causality tests and the Baron and Kenny mediation model to analyse the data. These methods are used to explore the extent to which herding behaviour exacerbates market overreaction and affects financial stability.Findings: The results reveal that herding behaviour exacerbates short-term market overreaction, leading to increased financial instability, particularly in BRICS markets. In contrast, herding behaviour does not significantly impact intermediate-term overreactions in developed markets. The study also finds that market overreaction significantly mediates the relationship between herding behaviour and financial stability.Practical implications: These findings have practical implications for policymakers. Understanding how herding behaviour and market overreaction impact financial stability can help formulate strategies to enhance market stability and mitigate systemic risks, particularly in more volatile BRICS markets.Social implications: Enhanced financial stability has broad social implications, including improved investor confidence and economic growth. Policymakers can use these insights to create more stable financial environments, which can lead to more robust economic development and reduced vulnerability to financial crises.Originality/value: This study provides new insights into the differential impact of herding behaviour and market overreaction on financial stability in developed and BRICS markets. By confirming the mediating role of market overreaction, this study enhances our understanding of financial market anomalies and contributes to the literature on financial stability.

This study examines the relationship between bank-specific variables, macroeconomic variables and non-performing loans (NPLs) in the seven countries of Southeast Asia (Cambodia, Indonesia, Malaysia, Philippines, Singapore, Thailand and Vietnam) during the pre-COVID-19[ ]and COVID-19 pandemic. This study adopts panel data regression and distributed lagged regression to examine the impact of bank-specific variables and macroeconomic variables as NPL determinants. The results show that bank-specific variables significantly correlate to NPL, but limited evidence indicates the influence of macroeconomic variables during pre-COVID. Nonetheless, macroeconomic variables are significant to NPL with the emergence of the pandemic, while the bank-specific variables are found to be insignificant. It shows that macroeconomic variables have a greater impact during the turbulent period as they affect most businesses, especially during the pandemic. Furthermore, macroeconomic variables are observed to have a stronger influence on developed countries, but the impact of bank-specific variables is stronger in emerging countries. The results of this study assist policymakers, regulators, banks and governments in identifying the determinants of high NPL as the indicator of a financial crisis. Greater emphasis shall be given to the changes in macroeconomic variables.

This study examines the existence, tendency and determinants of herding in the Malaysian stock market under market stress from 2016 to 2020. This study adopts ordinary least square and quantile regression models to estimate herding. Three types of measurements are used to capture volatility, which are realized volatility, Parkinson volatility and Garman and Klass volatility. The result shows that herding exists in the Malaysian stock market. Investors are observed to herd stronger in the bearish (down) market condition compared to bullish (up) market condition, especially in the upper quantile (τ > 50%). Realized volatility is found to be significant in every quantile except for the median quantile (τ = 50%) and Garman and Klass’s volatility is significant in the upper quantiles of 0.75 and 0.90. This study assists analysts and investors to formulate better investment strategies. Regulators and policymakers shall also control and regulate the herding behaviour of investors, which can deviate the stocks from their fundamentals. The existence of herding also violates the assumptions of EMH in assuming that investors are rational.

Purpose: This study examines the impact of firm-specific information and macroeconomic variables on market overreaction of US and Chinese winner and loser portfolio before and during COVID-19.Design/methodology/approach: The firm-specific information includes firm size, volume, volatility, return of asset (ROA), return of equity (ROE), earning per share (EPS) and quick ratio while the macroeconomic variables are export rate, import rate, real GDP, nominal GDP, FDI, IPI and unemployment rate. Besides, one-third of the top performance stocks are categorized as winner portfolio while one-third of lowest performance stocks are categorized as loser portfolio. This study uses AECR to indicate stock return and measure market overreaction. GAECR is used to determine contrarian profit. The data range of pre-COVID-19 is from 1-Jan-2015 to 31-Dec-2019 while the period of COVID-19 is from 1-Jan-2020 to 31-Dec-2020.Findings: In pre-COVID-19, firm-specific information (volatility, ROA, ROE and EPS) and macroeconomic variables are found to be correlated to stock return in US and Chinese portfolios except Chinese winner portfolio. Nonetheless, the impact of firm-specific information has vanished and macroeconomic variables are significant to stock return in COVID-19. It shows that investors rely on the economic indicators to trade in turbulent period due to emergence of COVID-19 as a disruption in market. Furthermore, US and Chinese portfolios are overreacted during COVID-19. Chinese loser portfolio has higher tendency of overreaction than US loser portfolio while US winner portfolio has higher tendency of overreaction than Chinese winner portfolio.Originality/value: The results of this study assists academician, practitioners and investors on understanding and create awareness to the existence of market overreaction and the determinants that can cause the phenomenon.

This study examines the impact of investor sentiment and market sentiment on overreaction in Europe and USA markets before and during COVID-19. The investor sentiment is calculated by the standard deviation, realized volatility, Parkinson’s estimator and Garman and Klass’s estimator. The market sentiment is measured by Business Confidence Index, Consumer Confidence Index, Labour Force Survey, Leading Index and Monetary Aggregates. The results of this study show that investor and market sentiments are correlated to stock return before COVID-19. Nonetheless, realized volatility is the only investor sentiment that is significant with the emergence of COVID-19. It shows that investors rely on the previous day’s stock prices to trade under market uncertainty. Market sentiment is observed to be insignificant in the pandemic. Furthermore, the existence of overreaction is detected in European portfolios but no evidence of overreaction is shown in the USA during pre-COVID-19. Surprisingly, overreaction is observed in Europe and USA markets in the pandemic. The USA market has a higher overreaction tendency than Europe. The results of this study assist academicians, practitioners and investors in understanding and creating awareness of the existence of market overreaction and its determinants before and during COVID-19.