The behavioural characteristics of the chief executive officer (CEO) such as narcissism can have different effects on the investment and financing of companies. Accordingly, the present study was conducted to investigate the effect of CEO narcissism on investment efficiency and financing methods of companies listed on the Tehran Stock Exchange. The statistical population of the study was all companies listed on the Tehran Stock Exchange between 2012 and 2017, of which 143 companies were surveyed as a statistical sample. The results of the analysis of research hypotheses using combined regression and logistic regression showed that CEO narcissism does not have a significant effect on overinvestment and underinvestment, but CEO narcissism has a significant positive effect on corporate investment efficiency. High CEO narcissism leads to increased corporate investment efficiency. The narcissism of the CEO has a positive and significant effect on domestic financing, but does not have a significant effect on external financing.
