The Effect of Coiffing Standards and Accounting Regulation on Bilateral Relationship between Level of Disclosure، Operational Performance and Market Valuation in the Firms Listed in Tehran Stock Exchange

This study examines of the disclosure behavior of listed companies in Tehran stock exchange and also the bilateral (two-sided) relationship between disclosure and operational performance / market valuation before and after important changes in economic and accounting regulation. Return on sale ratio and Tobin's Q are considered as operational performance and market valuation measures. an un-weighted disclosure index of 600 items has been used the level of disclosure in annual reports. In this regard¡ the goal of this research is to study the bilateral relationship between level of disclosure and operational performance and market valuation of 66 companies listed on Tehran Stock Exchange during 1998 until 2000 and 2008 until 2013. To analysis the collected data simultaneous equations system was estimated using two-step regression. Based on the results¡ there is bilateral relationship between the level of disclosure and operational performance and market valuation of the companies listed on the Tehran Stock Exchange before and after Important Changes in Economic and Accounting regulation. The results also show the level of disclosure and also the relationship between the level of disclosure and operational performance and market valuation have been increased after Important Changes in economic and accounting regulation