Precision medicines inherently fragment treatment populations, generating small-population markets, creating high-priced "niche busters" rather than broadly prescribed "blockbusters". It is plausible to expect that small markets will attract limited entry in which a small number of...

Using an aggregative games approach, we analyze horizontal mergers in a model of multiproduct-firm price competition with nested CES or nested logit demands. We show that the Herfindahl index provides an adequate measure of the welfare distortions introduced by market power, and that the induced...

We present a dynamic quantity setting game, where players may continuously adjust their quantity targets, but incur convex adjustment costs when they do so. These costs allow players to use quantity targets as a partial commitment device. We show that the equilibrium path of such a game is...

A central authority possessing tax and expenditure responsibilities can readily provide an efficient level of a public good. Absent a central authority, voluntary arrangements must replace coercive ones. Significant under-provision must be expected. International public goods are particularly...

This paper provides an algorithm for computing Markov Perfect Nash Equilibria (Maskin and Tirole, 1988a and b) for dynamic models that allow for heterogeneity among firms and idiosyncratic (or firm specific) sources of uncertainty. It has two purposes. To illustrate the ability of such models to...

Discretionary policymaking can foster strategic complementarities between private sector decisions, thus leading to multiple equilibria. This article studies a simple example, originating with Kydland and Prescott, of a government which must decide whether to build a dam to prevent adverse...