The objective of this research is to investigate the impact of product market competition on the relationship between leading ownership and stock price crash risk, as well as firm value, in companies listed on the Tehran Stock Exchange. For this purpose, four hypotheses were formulated to examine this issue, and data from 141 companies listed on the Tehran Stock Exchange for the period between 2015 and 2022 were analyzed. The research regression model was examined and tested using the panel data method with a fixed effects approach in Eviews10 software. The results obtained using the generalized least squares method at a 95% confidence level indicate that leading ownership has a significant negative impact on the stock price crash risk of the company. Additionally, leading ownership has a significant positive impact on the firm's value. Furthermore, the research findings indicate that product market competition does not have a significant impact on the relationship between leading ownership and stock price crash risk. The analysis of hypotheses related to product market competition does not show a significant impact on the relationship between leading ownership and firm value.
