The basis of investment in the capital market is the information issued by the companies, and if the distribution of information is not fair and symmetrical, the reaction of the investors will be contrary to reality, and this can affect the performance of the company; Therefore, the purpose of this study is to investigate the effect of information asymmetry on the performance of companies. The current research is applied and from the methodological point of view, the correlation is causal type (post-event). The statistical population of the research is all the companies admitted to the Tehran Stock Exchange, and using the systematic elimination sampling method, 131 companies were selected as the research sample in the period of 2012-2021. In order to measure the information asymmetry, the method of the range of the proposed price of buying and selling shares and to measure the performance of the company, the Q-Tobin ratio has been used. The results of the research hypotheses test showed that there is an inverse and significant relationship between information asymmetry and company performance.