Information in Equity Markets with Ambiguity-Averse Investors

Abstract

This paper shows that persistent mispricing is consistent with a market that includes ambiguity-averse investors. In particular, ambiguity-averse investors may prefer to trade based on aggregate signals that reduce ambiguity at the cost of a loss in information. Equilibrium prices may therefore fail to impound publicly available information. While this creates profit opportunities for ambiguity-neutral investors, ambiguity-averse investors perceive that the benefit of ambiguity reduction outweighs the cost of trading against investors who have superior information. The model can explain both underreaction, such as that evident in postearnings announcement drifts and momentum, and overreaction to accounting accruals. The Author 2008. Published by Oxford University Press on behalf of The Society for Financial Studies. All rights reserved. For Permissions, please email: journals.permissions@oxfordjournals.org, Oxford University Press.