摘要
The paper asserts that the misperceptions of noise traders are a behavioral bias characterized by overreactions. By introducing the overreaction coefficient, we provide an explanation for the volatility of asset prices and bubbles in a simplified framework that is similar to the DSSW （1990a） model. When the underlying asset is involved with a fundamental shock, noise traders will generally overreact to it, which creates an ＂overreaction risk＂. This kind of risk will make the asset prices more volatile, and even make up asset bubbles. Therefore, asset bubbles can be regarded as a psychological phenomenon, and are actually the results of the psychological changing process of noise traders.
