This paper surveys recent work on competition in markets in which consumers face costs to switching between competing firms' products, even when all firms' products are functionally identical. I address issues in macroeconomics, international trade and industrial organization: In a market with...

What should be the West's top priority for climate-change policy? This article is a revised and updated version of my talk to the Potsdam Global Sustainability Symposium (which drafted the Potsdam Declaration presented to the 2007 UN Climate Change Conference in Bali).

Switching costs and network effects bind customers to vendors if products are incompatible, locking customers or even markets in to early choices. Lock-in hinders customers from changing suppliers in response to (predictable or unpredictable) changes in efficiency, and gives vendors lucrative ex...

The existence of a ‘bidding market’ is commonly cited as a reason to tolerate the creation or maintenance of highly concentrated markets. We discuss three erroneous arguments to that effect: the ‘consultants’ fallacy’ that ‘market power is impossible’, the ‘academics’...

I explore the trade-off between a patent's length (that is, its lifetime) and its width (that is, its scope of coverage). A wider patent generally reduces the distortion of consumers' choices between the patented brand of the product and unpatented, lower-priced varieties sold by competitors but...

A firm that offers an additional product can capture business from rival firms for other products when consumers prefer to concentrate their purchases at a single supplier. This may lead firms to offer excessive product variety from the social standpoint. A firm may even completely foreclose...

Setting a price that results in rationing may be optimal for a seller whose customers must make a specific investment to be able to use its product. Rationing results in ex-post inefficiency, but the resulting distribution of ex-post surplus can compensate consumers for their...

This is an Invited paper for the World Congress of the Econometric Society held in Seattle in August 2000. We discuss the strong connections between auction theory and "standard" economic theory, and argue that auction-theoretic tools and intuitions can provide useful arguments and insights in a...

Part ownership of a takeover target can help a bidder win a takeover auction, often at a low price. A bidder with a ‘toehold’ bids aggressively in a standard ascending auction because its offers are both bids for the remaining shares and asks for its own holdings. While the direct effect of...