處份效果係指人們在從事證券交易時，傾向於實現獲利的股票卻又不願處份損失的部位。由於 Tversky and Kahneman (1992) 所提出的價值函數無法解釋處份效果，因此，本文在展望理論的基本精神之下，建構出一個 tanh (x)型態的價值函數，除了可以解釋處份效果，也解決了財富變動量趨近於零時風險偏好不合理的現象。

The definition of the disposition effect is when investors tend torealize profit gains, but are reluctant to realize losses. Because the valuefunction proposed by Tversky and Kahneman (1992) cannot explain thedisposition effect, we develop a tanh (x)-form value function by using theessence of the prospect theory. This explains the disposition effect andsolves for the phenomenon of unreasonable risk attitudes when thechange of wealth approaches zero.