The purpose of this study is investigating the Status Quo Bias (SQB) from suggested biases in behavioral finance. People who are subject to a SQB tend to choose an alternative that was chosen previously (i.e., their status quo) even if it is not the optimal choice any more. Status quo bias existence was investigated in this study using Ruenzi and Kempf (2005) model among investment companies listed in Tehran's Stock Exchange during 2003-2010. The data is collected quarterly from investment companies. Also, Stata10.0 software package is used for statistical analysis. The result shows the existence of a SQB is not found in Tehran Stock Exchange.