A Note on Wealth Effect under CARA Utility

Abstract

There is a simple but overlooked way of capturing the wealth effect under CARA utility via making the absolute-risk aversion parameter wealth-dependent. We implement this approach in the asymmetric information setting of Verrecchia (1982), and compare it with the alternative approach of changing the utility function (Peress, 2004). Ours is a straightforward tractable extension of Verrecchia, while Peress has to resort to approximate methods. Importantly, our closed-form solution reveals that the relation between wealth and wealth share invested in a risky asset can be negative, while Peress's main result is that this relation is uniquely positive.