New York has long been considered one of the most significant antitrust jurisdictions in the United States, dating back to the inception of legislation prohibiting anticompetitive conduct – the federal Sherman Act in 1890 and Clayton Act in 1914, and, in New York State, the Donnelly Act in 1899. New York’s status as a centre for finance, commerce, technology, sports, and entertainment has made it the venue of precedent-setting antitrust litigation brought by federal and state authorities and private litigants alike.

The modern framework for analysis of monopolisation claims was articulated in New York in 1945 by legendary jurist Learned Hand in the federal Court of Appeals for the Second Circuit’s decision in United States v Aluminum Co. of America (ALCOA); the Second Circuit refined its monopolisation analysis in 1979, in Berkey Photo v Eastman Kodak. In the intervening decades, in addition to further developing the law of monopolisation, New York’s federal courts have issued leading decisions addressing standing, antitrust injury, and, critically, horizontal restraints. Noteworthy antitrust cases venued in New York have involved computers (IBM), telecommunications (Bell Atlantic), credit cards (American Express), debit card services (Visa), digital advertising (Google), ticketing services (Live Nation and Ticketmaster), movie theatre ownership (Paramount), music licensing (ASCAP, BMI), professional baseball and football (MLB, NFL), and other industries too numerous to list.

New York’s Federal and State Courts

New York’s federal courts encompass the United States Court of Appeals for the Second Circuit (which also includes Connecticut and Vermont), and the United States District Courts for the Southern, Eastern, Northern, and Western Districts of New York. The courthouses for the Second Circuit and the Southern District of New York are directly adjacent to the Financial District in lower Manhattan, likely explaining why those courts have always been a hub for sophisticated, high-stakes business and financial litigation, including antitrust; that expertise likewise carries across the East River to Brooklyn, the home of the Eastern District of New York.

In addition to the large number of antitrust actions initiated in the Southern and Eastern Districts, those courts – particularly the Southern District of New York – are frequently selected by the federal Judicial Panel on Multidistrict Litigation to coordinate pretrial proceedings for multiple related cases filed throughout the country which share common questions of law or fact. Currently, of the 159 multidistrict litigations (MDLs) pending in US federal courts nationwide, 14 are in the Southern District of New York, and three are in the Eastern District; of 34 antitrust MDLs across the United States, four are in the Southern District of New York, and one is in the Eastern District. In these MDL proceedings, the New York transferee court applies the Second Circuit’s substantive law rather than the law of the transferor courts, further extending the influence of New York’s federal courts over the development of antitrust jurisprudence.

In New York’s state court system, the highest court, called the Court of Appeals, is located in Albany, the state capital. New York’s intermediate appellate courts, collectively the Appellate Division, have four Departments: the First (located in Manhattan), Second (Brooklyn), Third (Albany), and Fourth (Rochester). Anachronistically, New York’s trial-level courts are dubbed the Supreme Court, with one court in each of New York’s 62 counties. The New York Court of Appeals rarely decides antitrust matters; its most recent decisions concerning New York’s antitrust statute, the Donnelly Act, were in 2024 and, before that, 2012. By contrast, the Appellate Division – and particularly the First Department – hears such appeals routinely.

The Legal Framework for Antitrust Claims in New York

Federal antitrust claims are governed by the Sherman Act and the Clayton Act. Section 1 of the Sherman Act declares contracts, combinations, or conspiracies in restraint of trade to be illegal. Section 2 makes it unlawful to monopolise, or attempt to monopolise, any part of trade or commerce. The Clayton Act gives the federal courts jurisdiction over private litigation asserting claims under the Sherman Act and encourages such enforcement by entitling prevailing antitrust plaintiffs to recover treble damages sustained plus the cost of suit, including reasonable attorneys’ fees. Decisional law from the United States Supreme Court holds that only direct purchasers (often middlemen) of goods or services directly sold by an antitrust conspirator may sue under the federal Sherman Act.

State antitrust claims arise under New York’s Donnelly Act, which resembles Section 1 of the Sherman Act and also awards successful litigants treble damages and reasonable attorneys’ fees and costs. However, the Donnelly Act does not presently allow claims for monopolisation absent a conspiracy. On the other hand, the Donnelly Act does not limit permissible claimants to direct purchasers; it permits suit by indirect purchasers who suffered harm in New York, including consumers. Interestingly, class action lawsuits under the Donnelly Act are not permitted in New York state court, but can be asserted in federal court, with the result that class claims on behalf of indirect purchasers are often appended to federal court complaints for injunctive relief under the Sherman Act.

Trends and Developments in the Second Circuit Court of Appeals

The Second Circuit has recently issued three significant decisions regarding early-stage threshold issues for federal antitrust lawsuits.

DirecTV v Nexstar Media Group – In a split decision, the Second Circuit addressed and arguably expanded the scope of allegations that will be sufficient to satisfy plaintiffs’ “antitrust injury” and standing requirements in federal antitrust cases. 

The plaintiff alleged that the defendants engaged in a horizontal price-fixing conspiracy to force it to overpay for the right to retransmit the “Big-4” television stations (ABC, CBS, NBC, and Fox) or face the loss of programming. When DirecTV would not accede to their price demands, the defendants blacked out its programming, allegedly causing substantial lost profits when thousands of customers cancelled their subscriptions. The district court dismissed DirecTV’s antitrust claims, finding it had not suffered an antitrust injury and was not an efficient enforcer of the antitrust laws.

The Second Circuit reversed, with a two-judge majority of the panel holding that output reduction (the blacked-out stations) and lost profits constituted cognisable antitrust injury in a horizontal price-fixing case. The court rejected the view that antitrust injury in such cases must be limited to payment of supracompetitive prices. Instead, it held that a buyer who refuses to pay allegedly fixed prices and loses access to supply may suffer a direct injury from reduced output – potentially broadening the categories of plaintiffs able to bring antitrust claims.

However, in a dissent, a lone judge opined that the fact that DirecTV did not actually pay higher prices resulting from the alleged price-fixing meant it had not suffered a direct injury, made its damages highly speculative, and rendered it an inefficient enforcer. According to the dissent, the majority’s decision was the first by any US federal Circuit Court to hold that a “priced-out non-purchaser” plausibly alleged antitrust standing.

The defendants petitioned the United States Supreme Court for certiorari review. DirecTV waived its right to respond to the petition, but the Supreme Court requested that it file a response, ostensibly indicating at least some interest in the matter.

Mosaic Health v Sanofi-Aventis US – The Second Circuit reversed the district court’s dismissal of a putative class action lawsuit in which the plaintiffs alleged that insulin manufacturers conspired to restrict access to discounts under a federal programme requiring drug makers to reduce prices for certain clinics and hospitals to assist low-income patients. The lower court had dismissed the complaint on the ground that the plaintiffs’ allegations of parallel conduct by the four defendant drug companies were insufficient to support an inference of conspiracy.

The Second Circuit emphasised that, at the pleading stage, an antitrust plaintiff is required to demonstrate only “plausibility” that an illegal agreement existed, not “probability”. Specifically, regarding the sufficiency of allegations of parallel conduct, the court noted that the conduct in question need not be identical in every respect; general similarities in substance, timing, and effect may suffice when paired with plausible “plus” factors such as common motive, actions against self-interest, and interfirm communications.

The defendants petitioned for certiorari. As in DirecTV, despite the fact that the plaintiffs waived any response to the petition, the Supreme Court requested that they respond – again signalling at least some interest in the matter.

Sullivan v UBS AG – The Second Circuit partially reversed the dismissal of claims under the Sherman Act and other federal statutes against an assortment of banks and brokers for conspiring to rig the Euro Interbank Offered Rate, or Euribor, and to fix the prices of OTC Euribor-based derivatives. The district court had found there was no personal jurisdiction over any of the non-US defendants and dismissed all claims against them. It further held that only one antitrust claim, for collusive submission of false Euribor quotes, plausibly alleged the existence of a horizontal price-fixing conspiracy, and dismissed the remaining antitrust claims.

On appeal, the Second Circuit reversed the dismissal as to two defendants, UBS AG and The Royal Bank of Scotland PLC. The court found that UBS and RBS had purposefully directed activities toward New York and that two plaintiffs’ claims arose out of those contacts, establishing specific personal jurisdiction. As to those defendants, the court then held that the plaintiffs adequately alleged a conspiracy – supported by quotations of chats and emails reflecting traders’ actual co-ordination of their Euribor submissions. Further, because the plaintiffs’ remaining allegations concerned their direct transactions with UBS and RBS, the direct purchaser requirement (which the court called the “first-step rule”) was satisfied.

Trends and Developments in the Southern District of New York

Although the three Second Circuit decisions discussed above might be read to suggest a liberalisation of the requirements for antitrust claims, the picture is considerably more complicated. At the appellate level and among the district courts that comprise it, the Second Circuit remains characterised by its case-by-base, fact-specific jurisprudence rather than by any clear doctrinal approach or preference. That is amply demonstrated by significant recent decisions from the Southern District of New York.

United States v Visa – New York’s courts have long experience with significant government and private enforcement actions targeting digital platforms, payment systems, and technology markets. That continues in United States v Visa, in which the district court denied Visa’s motion to dismiss claims brought by the Department of Justice alleging monopolisation and attempted monopolisation in the market for general purpose debit network services and the submarket for general purpose card-not-present debit network services.

Although Visa challenged the government’s product market definition as implausible, the court found that, at least at the pleadings stage, practical indicia plausibly suggested that debit networks were a distinct type of payment service without economic substitutes. The court noted that market definition is deeply fact-intensive and generally requires discovery. Meanwhile, the court credited as plausible the government’s theory that Visa used exclusive-dealing-like contracts with banks and merchants, as well as agreements with actual or potential competitors, to preserve its market position and prevent rivals from competing effectively.

In re Google Digital Advertising Antitrust Litigation – This matter is part of an MDL co-ordinating pretrial proceedings for all private federal actions relating to Google’s digital advertising business. The Southern District of New York applied issue preclusion based on findings following the trial of a prior Department of Justice enforcement action in the United States District Court for the Eastern District of Virginia – which Google had unsuccessfully sought to have added to the MDL in New York. The Southern District held that, in the 15-day bench trial of the Virginia action, Google had a full and fair opportunity to defend issues it conceded were substantially identical to those in the MDL. Therefore, the court precluded Google from relitigating certain important findings concerning the existence and scope of relevant markets, Google’s engagement in anticompetitive conduct supporting the plaintiffs’ claims that Google had wilfully acquired and maintained monopoly power, and the determination that Google had unlawfully tied its publisher ad server to its ad exchange.

This presages the possibility of private plaintiffs increasingly seeking to use government enforcement victories to streamline follow-on antitrust litigation, particularly in complex technology-platform cases. More broadly, the Visa and Google matters reflect that New York federal courts continue to engage seriously with antitrust theories involving digital infrastructure, two-sided markets, tying, exclusive dealing, market foreclosure, and platform dominance.

In re: LIBOR-Based Financial Instruments Antitrust Litigation – In a major ruling in the long-running LIBOR MDL, the Southern District of New York demonstrated that courts require rigorous proof once a case reaches summary judgment. The plaintiffs – buyers of financial instruments with interest rates tied to the London Interbank Offered Rate – claimed that 16 defendant banks had conspired to artificially suppress the rate in violation of the Sherman Act. The district court granted the banks summary judgment after finding the alleged conspiracy economically implausible, unsupported by direct evidence, and lacking strong circumstantial evidence (ie, defendants’ parallel conduct as well as plus factors) substantiating its existence. The court rejected the plaintiffs’ plus-factor arguments and their experts’ opinions that failed adequately to address alternative explanations, including the impact of the financial crisis.

In re ACTOS Antitrust Litigation – This litigation, which was commenced in 2013 and has already taken two trips to the Second Circuit, similarly reflects the difficulty of obtaining summary judgment in complex antitrust matters, this time in the pharmaceutical context. Takeda, the manufacturer of the diabetes medication ACTOS, is alleged to have violated the antitrust laws by misdescribing its patent rights to the Food and Drug Administration, with the effect of delaying the introduction of generic versions of ACTOS.

The parties cross-moved for summary judgment, with Takeda claiming its alleged misconduct was excused by the “regulatory compliance” defence, and the plaintiffs arguing that, based upon the undisputed facts, Takeda had monopoly power, which it wilfully maintained through misrepresentations to the FDA. In an exhaustive decision, the district court granted the plaintiffs partial summary judgment that the “willful maintenance” element of their monopolisation claim was satisfied – but otherwise denied both sides’ motions based upon factual disputes that require resolution by a jury.

Trends and Developments in New York’s State Antitrust Law

In contrast to New York’s federal law, the most significant developments in New York’s state antitrust law are legislative.

In October 2025, New York’s Governor signed into law a statute prohibiting the use of software and other algorithmic tools to co-ordinate data from multiple sources to recommend rental prices or other lease terms. Although numerous US cities have enacted similar bans, reportedly, New York is the first state to do so. The law punishes using such tools knowingly or with reckless disregard, and treats violations as anticompetitive conduct under the Donnelly Act. Enforcement can occur via criminal and civil actions brought by the New York Attorney General, and also through civil actions by private parties.

A much greater legislative development is looming, although it has yet to be enacted. In 2025, and again in 2026, the New York State Senate passed SB 335, the “Twenty-First Century Anti-Trust Act”. SB 335 aims to overhaul the 127-year-old Donnelly Act. The bill focuses on modernising restrictions on perceived dominant firms, reducing the showing needed to establish market dominance, and instituting a new pre-merger notification requirement.

Whereas the current Donnelly Act does not cover unilateral, monopoly conduct of the kind made unlawful by Section 2 of the Sherman Act, SB 335 includes an equivalent to Section 2 and prohibits “abuse of dominance”. This standard derives from EU competition laws, which make it unlawful for any single entity with a “dominant position” in the relevant market to abuse that position. Under SB 335, a company with market share of 30% as a buyer or 40% as a seller, which engages in anticompetitive practices (eg, refusal to deal, tying), could be found liable for abusing its dominance in the relevant market.

SB 335 also introduces a New York-specific pre-merger notification requirement. Under the federal Hart-Scott-Rodino Act, parties planning mergers over approximately USD150 million must notify the Department of Justice’s Antitrust Division and the Federal Trade Commission. Those agencies have 30 days to review the transaction, after which they can take no action and the deal can be consummated, or they can issue a “second request”, requiring a more detailed submission to the government. SB 335 would require that any merger proposed by someone within New York State which is reportable under Hart-Scott-Rodino also be reported to New York’s Attorney General, who, among other things, would then be required to consider the proposed transaction’s effect on the labour market and workers.

In 2025, after passing the state Senate, SB 335 moved to New York’s Assembly, where it was referred to the Economic Development Committee; however, the legislative session ended with no further action taken. So far, the bill’s course in 2026 is the same: passage in the Senate, delivery to the Assembly, and referral to Economic Development. Its future remains unknown.

New York State’s recent decisional law on antitrust issues is far more sparse than in New York’s federal courts. Substantive antitrust claims tend to be asserted in federal court under federal law; and, as described above, Donnelly Act claims by indirect purchasers who are harmed in New York are often appended to federal complaints under the federal courts’ supplemental jurisdiction. Nonetheless, a few recent state court rulings shed light on state court developments under the Donnelly Act in its current form.

In People v CVS Pharmacy, Inc., the State’s tying claim failed because it defined the market too narrowly around CVS’s own pharmacies. The trial court rejected that single-brand market theory and dismissed the complaint because it did not adequately explain why other pharmacies were not interchangeable substitutes; the Appellate Division affirmed. The case suggests that single-brand market definitions are disfavoured unless the plaintiff can show lock-in, lack of substitutes, or similar facts.

In Troise v NYC Department of Buildings, the plaintiffs alleged that, in violation of the Donnelly Act, government actors had conspired to interfere with their ability to provide continuing education courses. The trial court dismissed the claim because the plaintiffs failed to allege market-wide competitive harm or a conspiracy among competing economic actors, and the Appellate Division affirmed. The case reinforces that alleged harm to one plaintiff is not enough; the Donnelly Act requires harm to the competitive process. Similarly, in Oak Beverages, Inc. v D.G. Yuengling & Son, a case that principally involved New York’s Alcoholic Beverage Control Law, the plaintiffs also asserted a conspiracy claim under the Donnelly Act; the trial court dismissed that claim because the complaint failed to allege the nature and effect of the asserted conspiracy and how its impact restrained trade in the market, and, again, the Appellate Division affirmed.

Finally, although decisions from New York’s Supreme Court (the trial-level courts) tend to receive less attention, the ruling in People v Intermountain Management, Inc. is enlightening as it reveals the New York Attorney General’s willingness to use the Donnelly Act assertively, and in contexts beyond the usual (financial, technology, pharmaceutical).

The Attorney General challenged Intermountain’s acquisition and closure of a ski mountain business near Syracuse, New York, coupled with non-compete and no-poach restrictions, alleging harm to competition in the Syracuse-area season-pass skiing market. Intermountain argued that federal merger enforcement law under the Clayton Act was inapplicable under the Donnelly Act, and that the transaction eluded state law scrutiny because there was no multi-party conspiracy. The court disagreed, observing that the Donnelly Act’s scope may, in fact, be even broader than that of the federal Sherman Act, because the Donnelly Act “proscribes ‘arrangements’ in addition to contracts, combinations, and conspiracies’” – with liability possible where two or more entities had “a reciprocal relationship of commitment” even if they lacked identical motives and did not satisfy the legal definition of conspiracy.

The court held that, whether or not federal Clayton Act jurisprudence was considered, the transaction fell squarely within the scope of the Donnelly Act. It found the arrangement was a per se violation of the Donnelly Act, and, alternatively, was unlawful under quick-look scrutiny (essentially an abbreviated version of Rule of Reason analysis, which considers procompetitive justifications). As a result, the Attorney General was granted summary judgment. The court has not yet ruled on the appropriate remedies.

Intermountain demonstrates that the Donnelly Act remains a viable and potent litigation option, particularly for localised transactions that may not rise to the level of impact commonly perceived as warranting the cost, time, and effort to prosecute federal antitrust litigation. Such expanded pursuit of state law challenges may be increasingly relevant at times when aggressive federal antitrust enforcement is rare.