We build a model of the financial sector to explain why adverse asset shocks in good economic times lead to a sudden drying up of liquidity. Financial firms raise short-term debt in order to finance asset purchases. When asset fundamentals worsen, debt induces firms to risk-shift; this limits...

The crisis of 2007-09 has been characterized by a sudden freeze in the market for short-term, secured borrowing. We present a model that can explain a sudden collapse in the amount that can be borrowed against finitely-lived assets with little credit risk. The borrowing in this model takes the...

We use prices of equity index options to quantify the impact of extreme events on asset returns. We define extreme events as departures from normality of the log of the pricing kernel and summarize their impact with high-order cumulants: skewness, kurtosis, and so on. We show that high-order...

Identification problems arise naturally in forward-looking models when agents observe more than economists. We illustrate the problem in several New Keynesian and macro-finance models in which the Taylor rule includes a shock unseen by economists. We show that identification of the rule's...

We propose two metrics for asset pricing models and apply them to representative agent models with recursive preferences, habits, and jumps. The metrics describe the pricing kernel's dispersion (the entropy of the title) and dynamics (time dependence, a measure of how entropy varies over...

We model the opacity of over-the-counter (OTC) markets in a setup where agents share risks, but have incentives to default and their financial positions are not mutually observable. We show that this setup results in excess "leverage" in that parties take on short OTC positions that lead to...