US antitrust policy takes as its objective consumer welfare, not total economic welfare. With that objective, Joe Bain's definition of entry barriers is more useful than George Stigler's or definitions based on economic welfare. It follows that economies of scale that involve sunk costs may...

Two-sided platforms (2SPs) cater to two or more distinct groups of customers, facilitating value-creating interactions between them. The village market and the village matchmaker were 2SPs; eBay and Match.com are more recent examples. Other examples include payment card systems, magazines,...