I study the effects of risk and ambiguity (Knightian uncertainty) on optimal portfolios and equilibrium asset prices when investors receive information that is difficult to link to fundamentals. I show that the desire of investors to hedge ambiguity leads to portfolio inertia and excess...

I study the effects of aversion to risk and ambiguity (uncertainty in the sense of Knight (1921)) on the value of the market portfolio when investors receive public information that they find difficult to link to fundamentals and hence treat as ambiguous. I show that small changes in public...

We explore how the demand for a risky asset can be decomposed into an investment effect and a hedging effect by all risk-averse investors. This question has been shown to be complex when considered outside of the mean-variance framework. We restrict dependence among returns on the risky assets...

We derive the equilibrium asset expected returns when there is ambiguity in asset expected returns, as well as ambiguity in asset return variances. In our model, ambiguity risk is systematic in nature and is non-diversifiable. Under regularity conditions, expected asset returns are linearly...

We theoretically analyze how index investing affects financial markets using a dynamic exchange economy with heterogeneous investors and two Lucas trees. We identify two effects of indexing: lockstep trading of stocks increases market volatility and stock return correlations but reduction in...

In recent years, portfolio flows to emerging markets have become increasingly large and volatile. Using weekly portfolio fund flows data, the paper finds that their short-run dynamics are driven mostly by global “push” factors. To what extent do these cross-border flows and global risk...

We formulate a tractable continuous-time rational expectations model in which the agent is ambiguity averse and would like to robustify asset return specification. Ambiguity affects the portfolio rule and asset pricing both individually and collectively with risk. Independently existing...