The debt capacity of an asset is the maximum amount that can be borrowed using the asset as collateral. We model a sudden collapse in the debt capacity of good collateral. We assume short‐term debt that must be frequently rolled over, a small transaction cost of selling collateral in the event of default, and a small probability of meeting a buy‐to‐hold investor. We then show that a small change in the asset's fundamental value can be associated with a catastrophic drop in the debt capacity, the kind of market freeze observed during the crisis of 2007 to 2008.

Galí (2014) showed that a monetary policy rule that raises rates when bubbles exceed some steady-state benchmark can paradoxically lead to larger deviations from steady state. Nevertheless, this comment shows that a central bank can always dampen a bubble by setting a higher-than-expected rate, although it may have to raise the rate aggressively. This is a different point from the Miao, Shen, and Wang (2019) comment on Galí (2014). They showed that when the central bank targets a different steady state than Galí considered, raising rates when bubbles exceed this alternative benchmark leads to smaller deviations from steady state.

By using graphical representations of simple portfolio choice problems, we generate a very rich dataset to study behavior under uncertainty at the level of the individual subject. We test the data for consistency with the maximization hypothesis, and we estimate preferences using a two-parameter utility function based on Faruk Gul (1991). This specification provides a good interpretation of the data at the individual level and can account for the highly heterogeneous behaviors observed in the laboratory. The parameter estimates jointly describe attitudes toward risk and allow us to characterize the distribution of risk preferences in the population.

Revealing Preferences Graphically: An Old Method Gets a New Tool Kit by Syngjoo Choi, Raymond Fisman, Douglas M. Gale and Shachar Kariv. Published in volume 97, issue 2, pages 153-158 of American Economic Review, May 2007