The Examination of the Effect of Ownership Structure on Firm Performance in Listed Firms of Tehran Stock Exchange Based on the Type of the Industry

This study is aimed to determine the role of ownership structure on firm performance. Using panel dataregression analysis method, the role of variables of ownership structure which includes: ownership concentration,institutional ownership and institutional ownership concentration have been examined for 137 listed firms ofTehran stock exchange within the period 2001 to 2006. It is concluded that ownership concentration doesn’t haveany significant effect on firm performance but the effect of two other variables are significant: institutionalownership has positive significant effect on firm performance but the effect of concentrated institutionalownership is negative. In the next part of this research the effect of ownership structure on firm performancebased on type of the industry has been studied and it is concluded that the industry factor moderates thiseffectiveness relationship. The findings of this research shed light on the role of ownership structure plays incorporate performance and thus offer insights to policy makers interested in improving corporate governancesystem.