The Investigating Overreaction of Investors to Patterns of Past Financial Performance Measures in the Tehran Stock Exchange

Studies investing the market overreaction argue that investors overreact to past financial performance investors drive stocks with high historical financial measures above their fundamental values. On the other hand price of stocks with poor past financial performance are pushed below their fundamental value. Subsequently, when investors realize that their previous expectation have not materialized, stock price of these firms revert to their fundamental values. The current study investigates overreaction of stockholders in the Tehran stock exchange(TSE).we also examine the impact of book to market ratio and firm size on the overreaction. time frame of present study is eight years that is ranged from 1998 to 2005. Testing method in this study is portfolio test. For analyse of results are used statistic t test. Results of this research show that investors in the Tehran stock exchange overreact to sales, earning and return of stock but they don’t overact to cash flow.