In general screening problems, implementable allocation rules correspond exactly to Walrasian equilibria of an economy in which types are consumers with quasilinear utility and unit demand. Due to the welfare theorems, an allocation rule is implementable if and only if it induces an efficient...

This paper uses new data to reexamine trends in concentration in U.S. markets from 1994 to 2019. The paper's main contribution is to construct concentration measures that reflect narrowly defined consumption-based product markets, as would be defined in an antitrust setting, while accounting for...

We analyze data on tens of thousands of alternating-offer, business-to-business negotiations in the wholesale used-car market, with each negotiation mediated (over the phone) by a third-party company. The data shows the identity of the employee mediating the negotiations. We find that who...

We present both theory and evidence that increased competition may decrease rather than increase consumer welfare in subprime credit markets. We present a model of lending markets with imperfect competition, adverse selection and costly lender screening. In more competitive markets, lenders have...

Commercial radio spectrum use rights in the US are traditionally assigned using licenses over large geographic areas with 10- or 15-year terms, to encourage infrastructure investment. However, such long-term licenses are difficult to reassign as more valuable uses for spectrum arise. Licenses...

We show that dealer market power impedes the pass-through of monetary policy in repo markets, which is an important first stage of monetary policy transmission. In the European repo market, most participants do not have access to trade on centralized exchanges. Rather, they rely on OTC...