Over-reaction to Earning Adjustment based on Event Study Approach: Evidence from Tehran Stock Exchange

Over - reaction term occurred when investors in their decision making pay higher attention to new data than previous issued information such weighting to new information cause reactions more than what law expects before. Thus, in current event-survey method research, author attempts to study over reaction phenomena when delivery average positive and negative benefits. In this research, for data sample determination, it was used systematic omission method and finally a sample of 121 firms accepted at Tehran stock market through2006-2014 studied. For research hypothesis tests, first, each stock output function measured based on ARMA models and Abnormal Return predicted based on performed measurement for event span. Finally, evidently, it was used Significance- test in order to measure Abnormal Return meaningfulness. Results showed that in case of negative and positive benefits amendment consequently over reaction.