Survey the Effective Factors on Tobin's Index in Tehran Stock Exchange

2 Abstract: With the formation of the subject of separation between ownership and management and a wide conflict of interests between owners and managers, evaluating the performance of companies is considered by different groups including owners, creditors, government, stock holders and even managers. One of criteria in evaluating companies' performance is Tobin's Q. However, variable factors may be related to this indicator. The purpose of this research is to evaluate the relationship between market liquidity, changes in stock price, return on capital, financial leverage, return on assets and size of corporations with Tobin's Q indicator in stock exchange of Tehran. To evaluate this issue, 100 sample was selected from statistical society which included necessary information for a 6-year period of research from (2005-2010), then the information related to six independent variables was studied and Tobin's Q was considered as a dependent indicator. For a testing hypothesis, the statistical technique of liner regression was used. The meaningfulness of regression was tested by T and F statistics. Research findings show that there is no meaningful relationship among Tobin's Q and size of corporations. Tobin's Q has a meaningful relationship with market liquidity, stock price, return on capital, financial leverage and return on assets.