We document that the global scope and depth of the crisis the began with the collapse of the subprime mortgage market in the summer of 2007 is unprecedented in the post World War II era and, as such, the most relevant comparison benchmark is the Great Depression (or the Great Contraction, as...

We propose a new theory of systemic risk based on Knightian uncertainty (or "ambiguity"). We show that, due to uncertainty aversion, beliefs on future asset returns are endogenous, and bad news on one asset class induces investors to be more pessimistic about other asset classes as well. This...