This paper develops a theory of dynamic pessimism and its impact on asset prices. Notions of time-varying pessimism arise endogenously in our setting as a consequence of agents' concern for model misspecification. We generalize the robust control approach of Hansen and Sargent (2001) by...

This paper develops a theory of dynamic pessimism and its impact on asset prices. Notions of time-varying pessimism arise endogenously in our setting as a consequence of agents’ concern for model misspecification. We generalize the robust control approach of Hansen and Sargent (2001) by...

We study aversion to model ambiguity and misspecification in dynamic portfolio choice. Investors with relative risk aversion gamma 1 fear return persistence, while risk-tolerant investors (0 gamma 1) fear return mean reversion, to confront model misspecification concerns when facing a model...