We investigate what it means for one act to be more ambiguous than another. The question is evidently analogous to asking what makes one prospect riskier than another, but beliefs are neither objective nor representable by a unique probability. Our starting point is an abstract class of...

Investors have long debated what fraction, if any, of their portfolio's currency exposure they should hedge. Although the answers cover a broad range, often with dubious rationale, most informed investors agree that the solution should be based on mean-variance optimization, deployed either to...

We examine the impact of return predictability and parameter uncertainty on investors' long-term portfolio allocations in the context of disappointment aversion. We find persisting horizon effects, with stocks appearing progressively more attractive at longer horizons as opposed to shorter ones....

We investigate the dynamic consumption and portfolio selection problem of an agent who has an intertemporal preference with loss and risk aversion, as proposed by Choi et al. (2019a). We disentangle the effects of loss aversion from those of risk aversion on risk taking. We show by simulation...

Consider an investor trading dynamically to maximize expected utility from terminal wealth. Our aim is to study the dependence between her risk aversion and the distribution of the optimal terminal payoff . Economic intuition suggests that high risk aversion leads to a rather concentrated...

This paper explicitly solves, in closed form, the optimal consumption and port folio choice for an ambiguity averse investor in a Merton-type two assets economy where a risk premium follows a mean-reverting process. The investor's preferences are represented by the recursive multiple priors...

This paper develops a tractable dynamic model of competition between two risk-averse portfolio managers who attempt to outperform each other by trading in different stocks, reflecting asset specialization. We characterize explicitly the unique Nash equilibrium portfolio policies, and show that a...

This paper considers the robust equilibrium reinsurance and investment strategies for an ambiguity-averse insurer under a dynamic mean-variance criterion. The insurer is allowed to purchase excess-of-loss reinsurance and invest in a financial market consisting of a risk-free asset and a credit...

We consider an investor who faces parameter uncertainty in a continuous-time financial market. We model the investor's preference by a power utility function leading to constant relative risk aversion. We show that the loss in expected utility is large when using a simple plug-in strategy for...

This paper presents a framework for portfolio optimization that makes three departures from the traditional mean-variance approach. First, we optimize the portfolio over multiple horizons, reflecting the belief that long-term investors care about intertemporal gains and losses, as well as...