Technological change, from the advent of robots to expanded trade opportunities, tends to create winners and losers. How should government policy respond? And how should the overall welfare impact of technological change on society be valued? We provide a general theory of optimal technology...

How does market concentration affect the potency of monetary policy? The ubiquitous monopolistic-competition framework is silent on this issue. To tackle this question we build a model with heterogeneous oligopolistic sectors. In each sector, a finite number of firms play a Bertrand dynamic game...

We study targeted lockdowns in a multi-group SIR model where infection, hospitalization and fatality rates vary between groups--in particular between the "young", "the middle-aged" and the "old". Our model enables a tractable quantitative analysis of optimal policy. For baseline parameter values...

We present a theory of Keynesian supply shocks: supply shocks that trigger changes in aggregate demand larger than the shocks themselves. We argue that the economic shocks associated to the COVID-19 epidemic--shutdowns, layoffs, and firm exits--may have this feature. In one-sector economies...

We provide a price theory for incomplete markets that extends the traditional Walrasian analysis. We derive formulas expressing the consumption response to current and future changes in interest rates and income. Our analysis provides a natural decomposition of these responses into substitution...

This note isolates an overlooked economic force for the Ruble to appreciate in response to international sanctions limiting exports to Russia. The economic intuition is that when Russians are unable to buy the mix of foreign goods they wish, then foreign goods becomes less attractive, increasing...