Errors in survey expectations display waves of pessimism and optimism and significant sluggishness. This paper develops a novel theoretical framework of time-varying beliefs capturing these empirical facts. In our model, the dynamic beliefs arise endogenously due to agents’ attitude toward...

When the planning horizon is long, and the safe asset grows indefinitely, iso-elastic portfolios are nearly optimal for investors who are close to iso-elastic for high wealth, and not too risk averse for low wealth. We prove this result in a general arbitrage-free, frictionless, semi-martingale...

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 a robust optimal stopping problem with respect to a set P of mutually singular probabilities. This can be interpreted as a zero-sum controller-stopper game in which the stopper is trying to maximize its pay-off while an adverse player wants to minimize this payoff by choosing an...

This paper resolves a question proposed in Kardaras and Robertson [Ann. Appl. Probab. 22 (2012) 1576-1610]: how to invest in a robust growth-optimal way in a market where precise knowledge of the covariance structure of the underlying assets is unavailable. Among an appropriate class of...