Intellectual property owners often hold the rights to several patents, each of which is essential to make or use a product. We compare the welfare properties of package licenses, under which a licensee pays the same fee regardless of the number of technologies licensed, with component licenses,...

This is a survey of the economic principles that underlie antitrust law and how those principles relate to competition policy. We address four core subject areas: market power, collusion, mergers between competitors, and monopolization. In each area, we select the most relevant portions of...

The market values of online platforms, such as Yahoo, stem from their ability to monetize the clicks they generate for firms advertising on their sites. We exploit a unique dataset on clicks from one of Yahoo's price comparison sites to estimate the determinants of clicks received by online...

In this paper, we empirically measure the effect of the DIVX preannouncement in the DVD market. We do this by measuring the effect of potential (incompatible) competition on a network undergoing growth. We find that there are network effects in the DVD market and that the preannouncement of DIVX...

Economists often assume that a patent gives its owner a well-defined legal right to exclude others from practicing the invention described in the patent. In practice, however, the rights afforded to patent holders are highly uncertain. Under patent law, a patent is no guarantee of exclusion but...

In a winner-take-all duopoly market for systems in which firms invest to improve their products, a vertically integrated monopoly supplier of an essential system component may have an incentive to advantage itself by technological tying; that is, by designing the component to work better in its...

When a new firm enters a market and starts selling a spatially-differentiated product, the prices of existing products may rise due to a better match between consumers and products. Entry may have three unusual effects. First, the new price is above the monopoly price if the two firms collude...

Clearinghouse models of online pricing---such as Varian (1980), Rosenthal (1980), Narasimhan (1988), and Baye-Morgan (2001)---view a price comparison site as an "information clearinghouse" where shoppers and loyals obtain price and product information to make online purchases. These models...

We model a homogeneous product environment where identical e-retailers endogenously engage in both brand advertising (to create loyal customers) and price advertising (to attract "shoppers"). Our analysis allows for "cross-channel" effects; indeed, we show that price advertising is a substitute...

Three years ago, the Antitrust Division and the Federal Trade Commission revised their Horizontal Merger Guidelines to articulate in greater detail how they would treat claims of efficiencies associated with horizontal mergers: claims that are frequently made, as for instance in the recently...