This paper characterizes the stockholders overreaction thorough return and price mean reverting behavior in specified ten major industry groups in Tehran Stock Exchange (TSE). For investigation of mean reversion presence, we use corporate firms from ten specified industry groups traded on the Tehran Stock Exchange and using a random walk with drift model with data over the period 2009-2013 period and recursive estimation in stability diagnostics test. The primary objective of this paper is to investigate mean reversion phenomenon in ten major industries including maximum number of real and nonstrategic investors with two different methods on quarterly return and monthly price time series. The results indicate that mean reversion occurred in the returns of these industry group. In addition, we use two major Unit Root Tests as complementary and final analysis. Out results also indicate that mean reversion takes place, significantly in eight industry groups and price time series in two industry groups follow a random walk process.

The subject of initial public offering (IPO) and the unusual short-time return of compared with another stocks, allocated many studies and researches in world level and in stock market to itself. The studied researches pointed to the short-time return of IPOs, which are higher than market and its long term return in return. One of the main hypothesis of behavioral finance is overreaction that is the main factor of overreaction in investor behavior is representativeness heuristic. This paper investigates overreaction behavior on shares of IPOs in Tehran stock exchange by considering 2 strategies of buy and hold and cumulative average return. The study investigates the effects of different factors such as price, market value, prior return and trading volume on overreaction. The results show negative effects of price and transaction volume on overreaction. In another words, price and volume of transactions are lower (higher) and higher return (lower) and therefore increased overreaction.