investigation of the effects of ownership structure on firms value: evidence from tehran stock market

privatization advocates believe that transfer to private sector increases firm’s performance and value, business environment, and therefore economic growth and welfare improves. in this research, by using the 70 accepted firms in the tehran stock exchange for the period of 2005 to 2009, we investigate the effect of firm’s ownership structure on their value by applying generalized method of moments (gmm) and generalized least squares (egls) methods of estimations. ownership structure is divided into four categories including: state ownership, corporate ownership, institutional ownership and individual ownership. we use tobin’s q ratio as the value criterion. kao cointegration test results confirm long-run relationship among variables under investigation. estimated results also show positive and significant effect of institutional and corporate ownership and don’t confirm the effect of individual ownership on firm’s value and confirm efficient monitoring hypothesis.