Positive Information Shock, Investors’ Behavior and the Risk of Stock Price Crash

The purpose of the present study is to review the effect of positive information shocks on investors’ behavior and the risk of stock price crash in corporations accepted in Tehran Stock Exchange. This research has a practical objective and it is an ex-post facto study conducted by descriptive-causal method. The research statistical population consisted of all companies accepted in Tehran Stock Exchange from 2009 to 2011. Random sampling method with systematic deletion was used. For data collection and hypothesis testing, the researchers used the audited financial statements of corporations accepted in Tehran Stock Exchange (available in the library of Tehran Stock Exchange). For data analysis, multivariate linear regression technique was used. The research results indicated that positive information shocks have a significantly positive effect on investors’ behavior and the risk of stock price crash. Positive information shocks decrease disclosure of information, increase information risk, and decline information transparency which ultimately accelerate the crash risk in the stock exchange. In addition, the effect of positive information risks on the crash risk is under the influence of corporation features, supervisory mechanisms, and economic environment. According to the obtained results, it is suggested to the analysts to study the impact of information shocks on important variables effective in the performance of corporations and give the results to the users. Furthermore, minor investors should pay special attention to prevent concealment of bad news by the directors because stockholders' attention is oriented to others’ fuss and their non-expert comments which have filled the market environment and increase the crash risk of the stock price.