The relation between market return and the prediction of stock’s dispersion price has been widely investigated. Behavioural Finance and Capital Asset Pricing Model (CAPM) have reached conflicting results regarding this issue. Specifically, Standard Finance states that change in market return will correspond to an increase in dispersion because each stock differs in its sensitivity to market return. On the opposite Behavioral Finance argue that the presence of herd behavior would lead “security return not to deviate far from the overall market return” (Chang, Cheng and Khorana, 2000, p.1654) because “individual suppress their own beliefs and make an investment decision based solely on the collective actions, even when they disagree with its prediction” (Christie and Huang, p.31).