For a period starting in 2015, Apple, Google, and Microsoft became the most valuable companies in the world. Each was marked by an external developer ecosystem. Anecdotally, at least, developers matter. Using a formal model of code spillovers, we show how a rising number of developers can invert...

Should internet era merger policy differ from industrial era merger policy? Platform ecosystems rely on economies of scale, data-driven economies of scope, high-quality algorithmic systems, and strong network effects that frequently promote winner-take-most markets. Their market dominance has...

Do firms benefit from external as well as internal performance enhancements? Using proprietary information from a significant fraction of the API tool provision industry, we explore the impact of API adoption and complementary investments on firm performance. Data include external as well as...