Switching costs and network effects bind customers to vendors if products are incompatible, locking customers or even markets in to early choices. Lock-in hinders customers from changing suppliers in response to (predictable or unpredictable) changes in efficiency, and gives vendors lucrative ex...

Economists at the Federal Trade Commission pursue the agency’s competition and consumer protection missions. In this year’s essay, in antitrust, we discuss two recent mergers that involved Rx drugs: First, we describe key elements of the inquiry into the Express Scripts/Medco transaction in...