Under continual innovation, greater patent strength expands innovating firms’ profit against imitation, but also shifts profit from current to past innovators. We show how the impact of patents on innovation, as determined by these two opposing effects, varies with industry characteristics....

The effects of entry on consumer and total welfare are studied in a model of consumer search. Potential entrants differ in quality, with high-quality sellers being more likely to meet consumer needs. Contrary to the standard view in economics that more entry benefits consumers, we find that...

We extend the analysis of monopoly third-degree price discrimination to the empirically important case where marginal costs also differ between markets. Differential pricing then reallocates output to the lower-cost markets, hence welfare can increase even if total output does not, unlike under...

This paper studies a model of interpersonal bundling, in which a monopolist offers a good for sale under a regular price and a group purchase discount if the number of consumers in a group---the bundle size---belongs to some menu of intervals. We find that this is often a profitable selling...