Abstract
I present a new theory of oligopoly and markups in general equilibrium, based on an innovative, scalable hedonic demand system, which I take to the data for the universe of US public firms. In my model, firms compete in a network of product market rivalries that emerge endogenously out of the characteristics of the products they supply. I estimate that consumer surplus is almost three times as large as profits; decompose firm-level markups into metrics of quality-adjusted productivity and market centrality; and analyze the extent, evolution, and drivers of monopoly power in the United States between 1995 and 2021. (JEL D21, D43, D85, G34, L13, L14)