It is a core principle of antitrust law and theory that reduced market concentration lowers the risk of anticompetitive behavior. We demonstrate that this principle is fundamentally incomplete.Traditional models assume that firms interact only as competitors. We examine and model...

Many markets, including markets for IPOs and debt issuances, are syndicated: each winning bidder invites competitors to join its syndicate to complete production. Using repeated extensive form games, we show that collusion in syndicated markets may become easier as market concentration falls,...

The U.S. residential real estate agency market presents a puzzle for economic theory: commissions on real estate transactions have remained high for decades even though entry is frequent and costs are low. We model the real estate agency market, and other brokered markets, as a game in which...

We investigate the competitive effects of spot-price contracting, in which a buyer and seller contract to transact at a future date at the price prevailing in that market at that future date (the ``spot price''); such contracts are ubiquitous in the beef-processing industry, among others. We...