Double Marginalization with Cournot Oligopolies

Vertical mergers are known to potentially create an incentive for the merged firm to raise the price of inputs it supplies to its rivals (raising rivals’ cost [RRC]). At the same time, vertical mergers are known to create efficiencies in the form of elimination of double marginalization (EDM). Competitive effects of vertical mergers are evaluated as the net effect of RRC and EDM. Conventional antitrust techniques treat the two effects—RRC and EDM—as separable and analyze each in isolation before evaluating their net effect. We show that in an equilibrium treatment, RRC and EDM are not separable; instead, they are inseparably linked because the size of EDM is an important determinant of the strength of the RRC incentive. When the link between EDM and RRC is taken into account, predicted price effects of a vertical merger can turn out to be significantly different relative to those predicted by conventional techniques. Under certain commonly used assumptions, a vertical merger may even create an incentive for the merged firm to lower its rivals’ cost. The precise price effect depends on two things: the shape of demand and the bargaining power of the upstream input supplier in its price negotiations with downstream firms.

The antitrust enforcement Agencies’ 2020 Vertical Merger Guidelines (VMGs) introduce a nontechnical application of bargaining theory into the competitive assessment of vertical acquisitions. This bargaining theory has much in common with the theory of unilateral effects that is applied to horizontal mergers. The VMGs focus on post-merger price increases requires consideration of a vertical merger’s role in eliminating double marginalization (EDM). The problem occurs when two bargaining firms both have market power but are unable to coordinate their output. Assessing EDM bundles two themes that Ronald Coase developed in his two most well-known articles: “The Nature of the Firm” and “The Problem of Social Cost”. The first argued that the boundaries of a firm are determined by the firm’s continuous search to minimize costs. The second argued that two traders in a well-functioning market will achieve the joint-maximizing solution. Anti-interventionists rely heavily on Coasean arguments that unless high transaction costs get in the way firms will bargain to joint maximizing results. If that is true, then double marginalization will rarely provide a defense to a vertical merger. The law of vertical mergers deals largely with firms that transact with one another routinely, in legally enforceable buy-sell relationships. In a well-functioning vertical market durable double marginalization should be rare.

Competitive Harm from Vertical Mergers

We study the impact of vertical integration on pricing incentives in multiproduct industries. To do so, we exploit recent variation in vertical structure in the US carbonated-beverage industry. While the elimination of double marginalization with vertical integration is normally characterized as procompetitive, economic theory predicts that it may cause anticompetitive price increases in multiproduct industries. We indeed find that vertical integration causes price decreases in products with eliminated double margins but price increases in the other products sold by the integrated firm. These results provide new evidence of anticompetitive effects of vertical mergers. (JEL D22, D43, G34, L13, L22, L66)

Vertical Mergers and Input Foreclosure: Lessons from the AT&T/Time Warner Case

This article offers a practical guide to analyzing vertical mergers using the general approach to input foreclosure and raising rivals’ costs that is described in the 2020 Vertical Merger Guidelines that were issued by the U.S. Department of Justice and the Federal Trade Commission. The step-by-step analysis described here draws lessons from how that theory of harm played out in the lone vertical merger case that has been litigated by the antitrust agencies in recent decades: the 2018 challenge by the Department of Justice to the merger between AT&T and Time Warner. I testified in court as the DOJ’s economic expert in that case. I explain here how to quantify the increase in rivals’ costs and the elimination of double marginalization that are caused by a vertical merger and how to evaluate their net effect on downstream customers. I also explain how this economic analysis fits into the three-step burden-shifting approach that the courts apply to mergers under Section 7 of the Clayton Act. Based on my experience in the AT&T/Time Warner case, I identify a number of shortcomings of the 2020 Vertical Merger Guidelines.

Tying Noncompetitive Goods

The thesis of this article is that the gap left by the abandoned Vertical Merger Guidelines ( VMGs) is small, and that the gap should not be filled until a sound foundation for guidelines is built. The VMGs operated with a narrow scaffolding in a vast space of real-world decisions and a continuum of organizational forms. The illustrations in the VMGs were based on pricing models that show that anticompetitive exclusion may result from vertical mergers. But these models are incapable of generalization, and they do not account for investments, market uncertainty, contracting problems, information asymmetries, and governance issues. Perplexingly, the VMGs ignored research that considers such factors and illuminates a broad range of empirically verifiable efficiencies. The requisite foundation for effective vertical guidelines is not in place. Until it is developed, replacements will fail to screen vertical mergers that do not raise concerns and will not be of assistance when mergers are challenged. Antitrust scholars could advance the foundational work by developing authoritative briefs on topics such as anticompetitive exclusion, asset-specific investments, incomplete contracts and opportunistic behavior, information asymmetries and principal–agent problems, the purposes and effects of restrictive contracts, and the implications of network economies for the scope of firms.

Monopolists selling complementary products charge a higher price in a static equilibrium than a single (multiproduct) monopolist would, reducing both the industry profits and consumer surplus. Firms could instead reach a Pareto improvement by lowering prices to the single‐monopolist level. We analyze pricing data of railroad coal shipping in the United States. We compare a coal producer that needs to ship from A to C, with the route passing through B, in two cases: (1) the same railroad owning AB and BC and (2) different railroads owning AB and BC. We do not find that the price in case (2) is higher than the price in case (1), suggesting that the complementary monopolist pricing inefficiency is absent in this market. Our findings are robust to propensity score blocking, causal machine learning algorithms, and difference‐in‐differences analysis. Our results have implications for vertical mergers, tragedy of the anticommons, mergers of firms selling complements, elimination of double marginalization, and royalty stacking and patent thickets.

Vertical Disintegration: The Effect of Refiner Exit from Gasoline Retailing on Retail Gasoline Pricing

The net effect of vertical integration on consumer welfare depends on the magnitude of the price reductions resulting from the elimination of double marginalization at the integrated firm and the price increases resulting from higher input prices charged to unintegrated competitors. In this paper, we estimate both of these effects in the US gasoline industry by examining the change in relative retail gasoline prices following the vertical separation caused by refiners’ decision to exit gasoline retailing beginning in the mid-2000s. Using station-level price data from Florida and New Jersey, we find that double marginalization caused retail prices to increase by about 1.2 cents per gallon. Estimates of the effect of raising rivals’ costs, while sensitive to the choice of control group, are of a similar magnitude. On net, we find that the average retail price of gasoline was effectively unchanged as the result of vertical separation.

This paper studies how the buyer power of downstream firms can affect the market outcomes in both upstream manufacturing and downstream retail markets. In a two-tier oligopoly, where upstream firms are locked in a pair-wise exclusive relationship with their downstream retailers, we study the choice of firms between vertical merger and Nash Bargaining with twopart tariff regimes. On working with three cases of no vertical merger, single chain vertical merger and double chain vertical merger we find that joint profits of upstream and downstream firms are lowest when both channels choose vertical integration as compared to Nash Bargaining regime. We also find that Vertical integration is welfare enhancing because retail price will be minimum as upstream and downstream firms behave as a single entity. Hence for both single and double chain mergers, elimination of double marginalization is procompetitive. These results have implications for the enforcement of competition (antitrust) law.

Vertical Integration between Hospitals and Insurers

While the Horizontal Merger Guidelines issued by US antitrust enforcement agencies have been periodically revised since their first publication in 1968, the Vertical Merger Guidelines were last the subject of modification in 1984. Moreover, there appears to be little appetite within the agencies for revision; so interested parties are for the moment left with guidance which does not reflect contemporary economic theory, agency practice or the 2010 Horizontal Merger Guidelines. The aim of this article is to partially fill the gap left by this divergence, by providing both a modern analytical framework for the assessment of vertical mergers and illustrative examples of recent antitrust agency enforcement actions upon which practitioners and agency staff alike may rely. The article also identifies a number of legal and policy issues which would need to be considered were the Vertical Merger Guidelines to be revised. We hope that this article will facilitate a more rapid revision.

A Suggested Revision of the 2020 Vertical Merger Guidelines (May 2, 2021)