This paper studies optimal second-best corrective regulation, when some agents/activities cannot be perfectly regulated. We show that policy elasticities and Pigouvian wedges are sufficient statistics to characterize the marginal welfare impact of regulatory policies in a large class of...

This paper characterizes the optimal transaction tax in an equilibrium model of competitive financial markets. As long as investors hold heterogeneous beliefs that are not related to their fundamental trading motives and the planner calculates welfare using any single belief, a strictly positive...

This paper studies leverage regulation and monetary policy when equity investors and/or creditors have distorted beliefs relative to a planner. We characterize how the optimal leverage regulation responds to arbitrary changes in investors’ and creditors’ beliefs and relate our results to...

This paper studies optimal second-best corrective regulation, when some agents/activities cannot be perfectly regulated. We show that policy elasticities and Pigouvian wedges are sufficient statistics to characterize the marginal welfare impact of regulatory policies in a large class of...

This paper characterizes the optimal linear financial transaction tax in an equilibrium model of competitive financial markets. When belief disagreement induces excess trading on assets in fixed supply, two main results arise. First, the optimal tax is positive: although a (small) transaction...

I develop a model of money market funds (MMFs) to study the ability of sponsor support to provide stability to the industry. I find that strategic complementarities in the sponsors’ support decisions can make MMFs vulnerable to runs different from the canonical bank-runs: it may lead to runs...

Since Sandmo (1981), many articles have analyzed optimal fiscal policies in economies with tax evasion. All share a feature: they assume that the cost of enforcing the tax law is exogenous. However, governments often invest resources to reduce these enforcement costs. In a very simple model, we...