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...

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...

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...

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...

"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...