Investigating Impact of Market Structure and Asymmetric Information on Performance of Active Firms on the Tehran Stock Exchange in a Dynamic Model

In the stock market, information plays an important role, if there is information asymmetry in market, maybe over time, the market moves toward incomplete competition models. The Tehran Stock Exchange, as the largest and most integrated part of the Iran capital market, does not have much history and as a result, several factors affect the activities of this market. Therefore, in this study, we investigate the factors affecting the performance of these firms. For this purpose, the 40 active firms in the Tehran Stock Exchange whose data are available are considered. The required data of the study were collected from the Tehran Stock Exchange site, the Rahavard Novin software and balance sheets of these firms during the period of 2008-2018 and models are estimated using with STATA 14. The performance variable in this study has three proxies including ROA, ROE and EBT indexes. The data analysis was done with GMM Dynamic Panel. Two main variables of market structure and asymmetric information are examined. The results show that the former have a direct relationship and the later have an inverse relationship with firm performance. The results also indicate that the information asymmetry trend is increasing and monopolistic competition is the best description of the degree of competition among the active firms of the Tehran Stock Exchange.