How to Approach the Calculation of Overcharge by Multisided Platforms

The recent AMEX decision has introduced the economics of “multisided platforms,” “transaction platforms,” “indirect network effects,” and “two-sided analysis” into antitrust analysis. As is often the case, sometimes such descriptive words precede any precise, scientific definition. In this brief note, we will explore some generally accepted concepts, how they relate to measures of market power, and how they support the calculation of at least one source of antitrust damages, the