The net effect of financial innovation on portfolio risks depends on the quantitative strength of its effects on the uninsurable and the speculative variances. I consider a calibration of the model for new assets linked to national incomes of G7 countries, which were recommended by Athanasoulis...

I review the literature on financial speculation driven by belief disagreements from a macro- economics perspective. To highlight unifying themes, I develop a stylized macroeconomic model that embeds several mechanisms. With short-selling constraints, speculation can generate over- valuation and...

This thesis consists of four essays about "uncertainty" and how markets deal with it. Uncertainty is about subjective beliefs, and thus it often comes with heterogeneous beliefs that may be present temporarily or even forever. The first essay analyzes the effect of uncertainty, and the...

We study optimal monetary policy during temporary supply contractions when aggregate demand has inertia and expansionary policy is constrained. In this environment, it is optimal to run the economy hot until supply recovers. Positive output gaps in the low-supply phase lessen the negative output...

We analyze optimal monetary policy and its implications for asset prices, when aggregate demand has inertia and responds to asset prices with a lag. If there is a negative output gap, the central bank optimally overshoots aggregate asset prices (asset prices are initially pushed above their...

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...

We investigate the role of debt market policies in mitigating liquidity traps driven by household leverage. When borrowers engage in deleveraging, the interest rate needs to fall to induce lenders to pick up the decline in aggregate demand. However, if the fall in the interest rate is limited by...

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 an allocation to be belief-neutral efficient (inefficient) if it is efficient (inefficient) under any convex...

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....