The entire difference between a mild downturn and a devastating crisis is the occurrence of sharp fire sales of domestic assets and possibly foreign exchange and the ensuing collapse in the balance sheets of both the financial and nonfinancial sector. Why and how do such crises materialize? And...

I describe two amplifications mechanisms that operate during liquidity crises and discuss the scope for central bank policies during crises as well as preventive policies in advance of crises. The first mechanism works through asset prices and balance sheets. A negative shock to the balance...

"This paper proposes a model in which the decision maker builds an optimally simplified representation of the world which is "sparse," i.e., uses few parameters that are non-zero. Sparsity is formulated so as to lead to well-behaved, convex maximization problems. The agent's choice of a...

"This paper incorporates a time-varying intensity of disasters in the Rietz-Barro hypothesis that risk premia result from the possibility of rare, large disasters. During a disaster, an asset's fundamental value falls by a time-varying amount. This in turn generates time-varying risk premia and...