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Finding Monopoly: Antitrust Market Definition

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Herb Hovenkamp @sherman1890.bsky.social · 11d

My piece on "Finding Monopoly: Antitrust Market Definition" is in the Sep. 2025 CPI Antitrust Chronicle, part of a symposium on market definition in antitrust. No longer paywalled. papers.ssrn.com/sol3/papers....

Market definition and calculation of a market share remain the most popular antitrust approach to assessing the threat of monopoly. One historical met

Self-Preferencing in Retail Digital Marketplaces: Evidence from Transaction Data

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Herb Hovenkamp @sherman1890.bsky.social · 15d

Good piece by Antonie, Gonzales & Shao: self-preferencing occurs less on digital markets than in the old economy; consistent with fact that online consumers have lower search costs, and indicates flaws in Biden admin targeting of online markets. www.cornerstone.com/insights/art...

The authors analyze retail transaction data to explore self-preferencing practices.

www.cornerstone.com

What Do the Epic Games’ Lawsuits Against Apple and Google Say About the DOJ’s Apple Case? - ProMarket

Herb Hovenkamp @sherman1890.bsky.social · Sep 8

CoStar, 2025 WL 2573045 (9thCir) refused to dismiss a complaint alleging that monopoly power for Sherman Act §2 purposes could be inferred simply from the fact that D persistently charged higher prices than its rivals for years, saying nothing about margins or output restrictions.

Herb Hovenkamp @sherman1890.bsky.social · Sep 2

Yes, it's a win for Google, but I think a win for U.S. technology and its users as well, as well as appropriate recognition by the court that messing around with market structure in a market as dynamic as this one could spell disaster.

Mark Lemley @marklemley.bsky.social · Sep 2

Basically the only remedies are a ban on continuing the exclusive deals already found unlawful and a one-time obligation to share a part of Google's search-index (but not its quality rankings) with competitors.

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Herb Hovenkamp @sherman1890.bsky.social · Aug 17

The BrwnShoe factors for antitrust market definition can send judges to insane lengths to twist them. See Harley-Davidson, 2025 WL 2374859 (dissenter would find relevant market by interpreting BShoe's "unique production facilities" factor to mean "American made.").

Herb Hovenkamp @sherman1890.bsky.social · Aug 15

In Gibson the 9th Cir problematically rejected an antitrust claim that the “hub” in a hub-and-spoke conspiracy provided hoteliers with nonpublic price information and the hoteliers (“spokes”) agreed to “abide by” its pricing algorithm’s recommendations. cdn.ca9.uscourts.gov/datastore/op...

cdn.ca9.uscourts.gov

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Herb Hovenkamp @sherman1890.bsky.social · Aug 12

Promarket has published my paper on the Epic Games antitrust suits against Apple and Google Play, and their implications for the government’s own pending lawsuit against Apple, including some observations about market definition and remedies. www.promarket.org/2025/08/12/w...

Herbert Hovenkamp reviews Epic Games’ lawsuits against Apple and Google for restraining users’ ability to access Epic’s offerings through third-party app stores. A comparison of the two ecosystems she...

www.promarket.org

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Herb Hovenkamp @sherman1890.bsky.social · Aug 8

In Papa John's the court provisionally certified a class action of franchise food employees subject to a no-poach agreement; the court assumed that it was unlawful per se. Papa John's Employee and Franchisee Antitrust Litig., 2025 WL 225564 (WDKy. 8-7-2025).

Herb Hovenkamp @sherman1890.bsky.social · Aug 3

all true and maybe here too. Do you agree that the chances of SCT review on the market definition issue are extremely slim?

Jonathan B. Baker @jbbecon.bsky.social · Aug 3

Nested markets are fine if the facts support both. I could imagine, for example, markets for colas, all soft drinks, and all beverages. If all satisfy the hypothetical monopolist test, conduct that harms competition in any one of them (or more than one) would presumably violate the antitrust laws.

AI and Leveraging Strategies: Implications for Antitrust

Herb Hovenkamp @sherman1890.bsky.social · Aug 3

In the Google Play case they court rested on the jury's finding of an "Android-only" relevant market. The earlier case challenging the same conduct by Apple found a market for "mobile game transactions" that included both Android and Apple. Can both of them be correct?

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Herb Hovenkamp @sherman1890.bsky.social · Aug 2

Does AI support anticompetitive leveraging strategies? See Erik Hovenkamp's short and accessible paper: "spread of AI is likely to increase the prevalence and complexity of leveraging strategies in digital markets. This poses a challenge to antitrust." papers.ssrn.com/sol3/papers....

In product markets that rely heavily on artificial intelligence (AI), firms both use data and generate data. For a multiproduct firm, the data generated by one

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Herb Hovenkamp @sherman1890.bsky.social · Aug 1

EpicGames decision is a good example of a secondary refusal to deal, which should be treated more like tying rather than refusal to deal, where liability is hard to get. The "tie" is not reachable classically, because there is no agreement; instead, it is created by code.

The U.S. Supreme Court and the Merger Efficiency “Defense” - Network Law Review

Herb Hovenkamp @sherman1890.bsky.social · Jul 30

In Brantmeier v. NCAA, 2025 WL 2108638(MDNC July 29, 2025) the court certified an injunction and a damages class [23(b)(2) & (3)] of collegiate tennis players objecting to an NCAA rule limiting their participation (and compensation) in non-NCAA tennis tournaments and activities.

Herb Hovenkamp @sherman1890.bsky.social · Jul 19

In Quinton v. Amex, 2025 WL 1994848 (EDNY 7-7-2025) the court admitted testimony that Amex's anti-steering rule was unlawful "cross-subsidization" -- a rare case permitting theory that a pure wealth transfer from poorer to wealthier customers could be an antitrust violation.

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Herb Hovenkamp @sherman1890.bsky.social · Jul 14

My new piece in Network L.Rev. A trivial % of mergers are motivated by price. Nearly all are efforts to improve production by scale or uniting complements. So a merger “efficiency defense” is wrongheaded, and the Supreme Court has not embraced it. www.networklawreview.org/hovenkamp-ef...

Firms’ principal motives for merging are not to increase market power, but rather to improve firm outcomes through changes in internal operations or structure. Of the 17000+ mergers that occur annuall...

www.networklawreview.org

Antitrust’s Interdependence Paradox - Virginia Law Review

Herb Hovenkamp @sherman1890.bsky.social · Jul 4

Christopher Leslie has published a very interesting article on how antitrust can pursue tacit (implicit) collusion more effectively, especially in concentrated markets. Leslie, Antitrust's Interdependence Paradox, 111 Va. L. Rev. 787 (2025), virginialawreview.org/articles/ant...

Introduction Price-fixing conspiracies are the “supreme evil” that Congress intended antitrust laws to deter and to punish.1 1.See Verizon Commc’ns, Inc. v. Law Offs. of Curtis V. Trinko, LLP, 540 U.S...

virginialawreview.org

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Herb Hovenkamp @sherman1890.bsky.social · Jul 4

An interesting cert. petition in the SAP vs Teradata case asks the Supreme Court to get rid of the per se rule for tying arrangements -- well timed given the status of some big tech cases. SAP SE v. Teradata, 2025 WL 1810683 (2025). The lower court: 124 F.4th 555 (9th Cir 2025)

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Herb Hovenkamp @sherman1890.bsky.social · Jun 24

CoStar v Commercial Real Estate Exchange, 2025 WL 1730370 (9c 6-23-2025) sustained a rule of reason claim that the defendant unlawfully made its commercial real estate brokers sign exclusive agreements. Can someone monopolize real estate by monopolizing its brokers?

Trump Antitrust Officials Should Stay Focused on Labor Harms | The Regulatory Review

Herb Hovenkamp @sherman1890.bsky.social · Jun 23

In a piece in the Regulatory Review this morning Melissa Bredbenner and urge the new administration not to abandon the Biden administration's antitrust concerns about labor. www.theregreview.org/2025/06/23/b...

Heads of the Justice Department’s Antitrust Division and FTC should focus on harms to labor in merger review.

www.theregreview.org

Most antitrust offenses require proof of the defendant's market power, or ability to control the market and raise prices above cost. For example, many exclusive

Herb Hovenkamp @sherman1890.bsky.social · Jun 22

My “Antitrust and e-Markets” is coming out in Stan. L. & Pol’y Review. Segregating e-commerce, as courts often do, exaggerates digital market power, especially for the many products that are sold both off- and online where e-Markets reduce concentration. papers.ssrn.com/sol3/papers....

Antitrust and eMarkets

Herb Hovenkamp @sherman1890.bsky.social · May 30

In a good way, i trust!

Herb Hovenkamp @sherman1890.bsky.social · May 30

I hope your name is on the back.

Herb Hovenkamp @sherman1890.bsky.social · May 29

In fact, Rehnquist wrote a concurrence in Reiter, predicting the decision would "add a substantial volume of litigation to the already strained dockets of the federal courts, and could be used to exact unfair settlements from retail businesses."

Herb Hovenkamp @sherman1890.bsky.social · May 29

The SCT's first use of "consumer welfare" was in a case (Reiter v. Sonotone, 442US330) that made antitrust damages actions available to consumers. The result was a massive increase in consumer plaintiff jury trials. What this document say makes no sense and, in any event, contains no support.

American Economic Liberties Project @econliberties.bsky.social · May 29

Our judicial system funnels private plaintiffs out of court, away from juries, and into opaque arbitration processes that favor the wealthy and powerful.

@capitolkvd.bsky.social has the history, and the path forward, in her first for The Economic Populist.👇