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.

In this paper, we present an empirical investigation to measure the effects of various factors on operating loss in one of major Iranian banks called Bank Mellat. The proposed study of this paper uses a standard questionnaire and distributes it among 57 people who are mainly in top management levels. The questions are categorized into five groups including events related to the processes and methods, events outside the organization, related events within the organization and business disruptions and system failure. The results of our survey confirm that the loss associated with events related to the processes and methods increases operating risk meaningfully, the loss associated with business disruptions and system failure increases operating risk meaningfully and the loss associated with related events within the organization increases operating risk meaningfully. However, our survey do not confirm that the loss associated with events outside the organization increase operating, risk meaningfully. Finally, the preliminary survey of our analysis shows that there is not enough evidence to believe that the effects of business disruption and internal affairs are significantly different from the other event.