A 'folk theorem' originating, among others, in the work of Stiglitz maintains that competitive equilibria are always or 'generically' inefficient (unless contracts directly specify consumption levels as in Prescott and Townsend, thus bypassing trading in anonymous markets). This paper critically...

During extreme financial crises, all of a sudden, the financial world that was once rife with profit opportunities for financial institutions (banks, for short) becomes exceedingly complex. Confusion and uncertainty follow, ravaging financial markets and triggering massive flight-to-quality...

Belief disagreements have been suggested as a major contributing factor to the recent financial crisis. This paper theoretically evaluates this hypothesis. I assume that optimists have limited wealth and take on leverage in order to take positions in line with their beliefs. To have a...

We investigate the role of macroprudential policies in mitigating liquidity traps driven by deleveraging, using a simple Keynesian model. When constrained agents engage in deleveraging, the interest rate needs to fall to induce unconstrained agents to pick up the decline in aggregate demand....

I investigate the effect of financial innovation on portfolio risks when traders have belief disagreements. I decompose traders' average portfolio risks into two components: the uninsurable variance, defined as portfolio risks that would obtain without belief disagreements, and the speculative...

I illustrate the effect of financial innovation on portfolio risks by using an example with risk-sharing needs and belief disagreements. I consider two types of innovation: product innovation, formalized as an expansion of new financial assets; and process innovation, formalized as a reduction...

This paper proposes a welfare criterion for economies in which agents have heterogeneously distorted beliefs. Instead of taking a stand on whose belief is correct, our criterion asserts that an allocation is belief-neutral efficient (inefficient) if it is efficient (inefficient) under any convex...

While the traditional view of financial innovation emphasizes the risk sharing role of new financial assets, belief disagreements about these assets naturally lead to speculation, which represents a powerful economic force in the opposite direction. This paper investigates the effect of...