Abstarct: The main objective of this study is to investigate the impact of earnings management and overconfidence of investors on the performance of accepted companies in the Tehran Stock Exchange during the years 2011 to 2021, using the Panel Data method. The results of data analysis indicate that earnings management leads to a decrease in the return on assets (ROA) of the companies, while overconfidence of investors results in an increase in the market-baxsed valuation ratio of the company's stocks (Tobin's Q). These findings suggest that investment policies and management decisions in the context of earnings management have a direct effect on the financial performance and equity value of the companies. As a final recommendation, further studies focusing on different industries and various market conditions can provide a more detailed map of these relationships and assist economic decision-makers in facing the challenges and opportunities of the capital market.