In this article we distinguish between two types of single-firm conduct. The first, which we call "extraction," is conduct engaged in by the firm to capture surplus from what the firm has itself created independent of the conduct’s effect on rivals. The second, which we call "extension," is...

We demonstrate that demand uncertainty alone can lead to equilibrium product variety. We consider a simple environment in which when demand is certain, a social planner, a competitive market, and a monopolist would all offer a single product, but when demand is uncertain, a social planner, a...