Meybod University Strategic Management Accounting 3092-6890 2 1 2025 05 22 Investigating the relationship between managers' overconfidence and stock crash risk with emphasis on the mediating variable of company size Investigating the relationship between managers' overconfidence and stock crash risk with emphasis on the mediating variable of company size 91 120 222378 10.22034/smajournal.2025.522626.1022 FA Nima Osanlou Assistant Professor, Accounting Department, Rasht Branch, Islamic Azad University, Rasht, Iran Narjes Bagheri Solaymandarabi Accounting, Master's degree, Islamic Azad University, Rasht, Iran Journal Article 2025 05 10 The role of managers' personality traits and worldview on their professional judgment is not hidden from anyone, and therefore interpreting its dimensions can help control managers' emotions and excessive reactions to the spread of good and bad news about the business unit. Overconfidence, as a personality type that is rooted in exaggerated self-esteem, will have negative consequences on managers' estimates, evaluations, and most importantly, professional judgment. Therefore, in this study, we are looking for the relationship between managers' overconfidence and the risk of stock collapse. The correlation method has been used to analyze the data. The statistical population studied is 174 companies listed on the Tehran Stock Exchange. The results of the present study show that the more managers are optimistic about future events, the more their desire to invest will be, and consequently, the risk of stock collapse will increase. Also, the size of the company, as a moderating variable, will moderate and control the relationship between overconfidence and the risk of stock collapse. The role of managers' personality traits and worldview on their professional judgment is not hidden from anyone, and therefore interpreting its dimensions can help control managers' emotions and excessive reactions to the spread of good and bad news about the business unit. Overconfidence, as a personality type that is rooted in exaggerated self-esteem, will have negative consequences on managers' estimates, evaluations, and most importantly, professional judgment. Therefore, in this study, we are looking for the relationship between managers' overconfidence and the risk of stock collapse. The correlation method has been used to analyze the data. The statistical population studied is 174 companies listed on the Tehran Stock Exchange. The results of the present study show that the more managers are optimistic about future events, the more their desire to invest will be, and consequently, the risk of stock collapse will increase. Also, the size of the company, as a moderating variable, will moderate and control the relationship between overconfidence and the risk of stock collapse. https://www.smajournal.ir/article_222378_78c770a3f2d529a8993d480e8bf179d9.pdf