The effect of audit opinions and audit firm reputations on the stock prices of Vietnamese joint-stock companies during and after the COVID-19 pandemic

The research aims to analyze the impact of audit opinions and the reputation of audit firms on the stock prices of listed joint-stock companies in the Vietnamese stock market during and after the COVID-19 pandemic. Using a dataset of 672 joint-stock companies listed on the Vietnam stock market from 2020 to 2023 and employing the panel data Feasible Generalized Least Squares (FGLS) method, this research provides evidence of the significant positive effects of audit opinions and audit firm reputation on stock prices within the Vietnamese context. The findings reveal that stock prices during the COVID-19 pandemic were significantly higher than in the post-COVID-19 pandemic period, driven by investor psychology and excessive optimism. Moreover, the research points out that during the COVID-19 pandemic, investors paid less attention to audit opinions compared to the post-COVID-19 pandemic period. Finally, the research results also demonstrated that audit firms' reputations consistently influenced stock prices, regardless of the period. Based on these findings, the study offers several recommendations for investors, corporate managers, and government regulators.