On Abel's Concepts of Doubt and Pessimism.

In this paper, we characterize subjective probability beliefs leading to a higher equilibrium market price of risk. We establish that Abel's result on the impact of doubt on the risk premium is not correct in general; see Abel [2002. An exploration of the effects of pessimism and doubt on asset returns. Journal of Economic Dynamics and Control 26, 1075–1092]. We introduce, on the set of subjective probability beliefs, market-price-of-risk dominance concepts and we relate them to well-known dominance concepts used for comparative statics in portfolio choice analysis. In particular, the necessary first-order conditions on subjective probability beliefs in order to increase the market price of risk for all nondecreasing utility functions appear as equivalent to the monotone likelihood ratio property.