An Investigation of Effect of Disclosure Informational Noise on Risk and Return in Tehran Stock Exchange

The main purpose of this study is find effect of Prior-Period Adjustment (PPA) on risk and return of stock market. For measuring informational noise which existence in financial statements, we used Prior-Period Adjustments. Study show that companies usually using PPA for adjusting their past cumulative income or lose, in other word using PPA become traditional and commonly work. Firms mostly used PPA as implement for correct there overestimated performance issued in past. In addition statistical tests imply that PPA has significantly related with risk and return but this effect is appearing in duration of time. The research data was prepared by studying 4304firms-year data which have been active in Tehran Stock Exchange during 1378-1389.