The CEO's decision-making power plays an important role in achieving or not achieving organizational goals. Based on the findings of previous research, powerful managers make more risky decisions (Haider and Fang 2016) and this can increase the company's risk. However, the main focus of this study is to investigate the relationship between CEO power, company risk-taking and the role of ownership concentration in companies listed on the Tehran Stock Exchange. is. The statistical population screened according to the systematic elimination pattern in this study is 119 companies listed on the Tehran Stock Exchange and has been studied in the period between 1390 and 1397. Data analysis was performed using panel regression and Eviews software. In order to measure the company's risk-taking, the Fama French three-factor model has been used. The results showed that there is a significant relationship between CEO power and company risk-taking, but major shareholders have no effect on the relationship between CEO power and company risk-taking, as well as the effect of major shareholders on the relationship between CEO power and company risk-taking. Non-governmental companies were no different from state-owned companies.