摘要：This study investigates the effects of ownership structure on the performance of the listed companies in the Tehran Stock Exchange (TSE). Consequently, a main hypothesis is presented, which states that there is a significant relationship between companies' ownership structures and their performances and then five sub-hypotheses are provided. For testing the hypotheses, the statistical panel data technique is employed. For testing each hypotheses, 4 accounting and economics performance evaluation variables models based on different ownership structures are established. The statistical population includes 66 companies in the period between 2003-2008. Based on the research results, all hypotheses except the fourth one, were confirmed. The findings revealed a significant negative relationship between the institutional ownership and companies' performances; and the relationship between corporate ownership and companies' performance generally was significantly positive. Management ownership, however, would affect the performance significantly and negatively. For foreign ownership, there was no information that would indicate ownership of the foreign investors in our samples companies. With respect to the company ownership, just in the models based on the accounting variables (i.e., ROA and ROE) coefficients are significant and negative. But in the models based on the market variables (i.e., Q-Tobin and MBVR) coefficients are not significant. In general, there was a significant relationship between companies' ownership structures and their performances.
