d and protected by entry barriers. In the absence of such structural features, these formal models recognize that vertical integration may be just as likely to lower price and increase welfare and that the ability of existing players or new entrants to expand their outputs will be sufficient to defeat any attempt to increase price above competitive levels. 23 In other words, the post-Chicago literature incorporates the same structural preconditions discussed above for vertical integration to harm competition. The primary exception to this conclusion is a scenario contained in Michael Whinston's seminal analysis of tying (1990), 24 in which an input producer assumed 20 See, e.g., Standard Oil Co. V. United States (Standard Stations), 337 U.S. 293, 295, 314 (1949) (holding that exclusive dealing contracts may be held illegal even absent proof of any tendency to create monopoly and that foreclosure of 16% of market was sufficient to render exclusive dealing contract illegal); Brown Shoe Co., 62 F.T.C. 679, 687 10, 691 g 33 (1963) (invalidating exclusive dealing arrangement even though it only foreclosed less than 1% of retail outlets), aff'd 384 U.S. 316, 321-22 (1966). 21 Eleven Line, Inc. V. N. Tex. State Soccer Ass'n, 213 F.3d 198, 206 n. 16 (5th Cir. 2000) (recognizing circuit split). Lantec, Inc. V. Novell, Inc., 306 F.3d 1003, 1024 n. 11 (10th Cir. 2002) (same); cases collected in Areeda and Hovenkamp (2008a, pp. 135-40). Peltzman (1969); Blair and Kaserman (1985); Areeda and Hovenkamp (2008c). 23 Salinger (1991); Riordan and Salop (1995). 24 The analysis of Whinston that follows draws on Yoo (2007a, 2008). Antitrust as Applied to Network Industries to face competition from an inferior product uses a credible precommitment to tying in order to harm competition in an adjacent market, a situation that Whinston recognized was equivalent to vertical integration. 25 Interestingly, Whinston's model assumes a wide variety of restrictive conditions that not only largely incorporate the structural preconditions discuss