SUMMARY
Liquidity is one of the concerns of those who attempted to take stock or mange the equation infrastructure. One indicator of the stock market situation, the liquidity of the securities included in it. Two factors effect on the liquidity included systematic volatility and unsystematic volatility. The probability of real output than what is expected, define on stock returns liquidity, stock returns liquidity including systematic volatility and unsystematic, increased systematic volatility increasing stock liquidity and increased unsystematic volatility will reduce the liquidity of the stock. On the basis of this study, the effect of systematic volatility and unsystematic on the liquidity is evaluated using Amivest criterion. This research in terms of purpose applied and type descriptive - correlational study, based on three hypotheses were tested. For this purpose, a sample of 95 companies among all companies listed in Tehran Stock Exchange, the time return 2009 to 2013 by systematic elimination method according to the results achieved, stock returns volatility effect on stock liquidity so that systematic volatility of stock returns leading to increased stock liquidity and increased stock returns unsystematic volatility leading to reduces the stock's liquidity.