Key Trends in State Antitrust Enforcement

Companies can no longer afford to treat the states as an afterthought when it comes to antitrust enforcement. Recent examples demonstrate the states are powerful enforcers in their own right:

• State enforcers took over the prosecution of the antitrust case against LiveNation and Ticketmaster when the DOJ settled a few days into trial, achieving a landmark victory after a hard-fought jury trial.
• A multistate coalition seeking to block the Nexstar/Tegna merger—which had already received federal clearance—recently succeeded in persuading a court to issue a preliminary injunction prohibiting further integration.
• Another multistate coalition is currently challenging the Hewlett Packard Enterprise/Juniper Networks DOJ settlement, alleging that the deal, beyond being anticompetitive, was the product of improper political influence.

All signs suggest that this ramped-up enforcement is here to stay. States have increased the budgets for Attorney General offices, created dedicated antitrust divisions within those offices, and opened new roles for antitrust enforcers, many of which have been filled by experienced DOJ Antitrust Division and FTC alumni.¹ The states have also brought in external resources where necessary—forming multistate coalitions with other State Attorney General offices to prosecute significant matters, hiring outside counsel to represent them in litigation, and/or prosecuting cases alongside private plaintiffs who can shoulder some of the resource burden. This alert examines key trends in state antitrust enforcement that companies should be aware of as they navigate this evolving landscape, including developments in Big Tech, algorithmic pricing, ESG, healthcare, merger enforcement, and criminal antitrust prosecutions.

Enforcement Priorities

Big Tech. Concentration in technology markets, with a focus on the Big Tech companies, has been a significant priority for state Attorney General offices in recent years. Working alongside the DOJ, a multistate group of Attorney General offices prosecuted Google for conduct relating to its Search and AdTech products—winning liability verdicts in both cases. Sixteen states have joined the DOJ’s ongoing monopolization suit against Apple relating to the iPhone and Apple Watch.² And nineteen states and territories have banded together with the Federal Trade Commission to prosecute Amazon for alleged monopoly maintenance and unfair competition.³

The states have also struck out on their own to prosecute Big Tech companies. California, for example, is a party to the FTC lawsuit against Amazon, but it is also separately seeking a preliminary injunction against Amazon for allegedly fixing prices.⁴ Solo multistate prosecutions are also on the upswing. For instance, a bipartisan multistate coalition pursued antitrust claims against Google concerning its operation of the Google Play Store, which they prosecuted with the assistance of outside trial counsel and litigated alongside private plaintiffs. The states ultimately settled the matter shortly before trial for significant monetary and injunctive relief.⁵

Given the states’ success in the Google antitrust cases, and the importance of Big Tech to consumers and the economy more broadly, we can expect the states to remain active in prosecuting antitrust cases against Big Tech, including emerging AI technologies.

Algorithmic Pricing. While Big Tech receives a good deal of attention, it is far from the states’ only enforcement priority. Companies that provide or use algorithmic pricing software have drawn the states’ attention. Several states, including Arizona, California, Maryland, Washington, and the District of Columbia, have filed suits under their state antitrust laws challenging the use of algorithmic pricing software in housing rental markets.⁶ Other states joined the DOJ suit challenging the same conduct.⁷ Similarly, a multistate group has joined the DOJ’s antitrust lawsuit against Agri Stats, a firm that aggregates and distributes information for meat processors.⁸

Rather than leave the lawfulness of pricing algorithms solely to the courts, California, New York, and Connecticut have passed legislation prohibiting certain uses of algorithmic pricing tools.⁹ Similar legislation is pending in other states.¹⁰

ESG. Environmental, social, and governance initiatives have also attracted the scrutiny of state antitrust enforcers. Arguing that ESG collaborations are actually unlawful cartels, certain state Attorney General offices have begun investigating climate alliances, net-zero commitments, and sustainability standards.¹¹ Eleven states, for example, recently sued asset managers BlackRock, State Street, and Vanguard, alleging that their stock acquisitions of certain coal companies were anticompetitive.¹² In February 2026, the states settled with Vanguard for $29.5 million and an agreement that it would “avoid imposing ESG goals over its customers’ profitability.”¹³ Another multistate coalition has issued notice letters to nearly 80 corporations associated with the U.S. Plastics Pact and other environmental organizations, warning that coordinated plastics recycling initiatives may violate state and federal antitrust and consumer protection laws.¹⁴ And the FTC and a group of eight state attorneys general recently filed—and, on the same day, entered into stipulated permanent injunctions resolving—a lawsuit against advertising giants Dentsu, GroupM Worldwide (also known as WPP Media), and Publicis alleging that the companies’ adherence to ESG-driven brand-safety standards was really a coordinated boycott of certain disfavored media outlets.¹⁵ The states’ use of their antitrust laws to challenge conduct previously viewed as unproblematic—like adherence to sustainability or brand-safety standards—underscores the importance of understanding shifting state priorities.

Healthcare. State enforcers have also intensified their scrutiny of healthcare markets. State attorneys general have, for example, aggressively prosecuted pharmacy benefit managers (“PBMs”) for alleged anticompetitive conduct. Louisiana and Oklahoma recently settled lawsuits against PBMs for $45 million and $32 million, respectively.¹⁶ Hawaii and Vermont are currently litigating claims that PBMs artificially inflated the list price of life-saving medications like insulin.¹⁷ The states have also begun pressuring the federal government to require more transparency from PBMs. For example, 45 attorneys general recently urged the Department of Labor to promulgate a rule requiring increased transparency in how PBMs set drug prices.¹⁸

Many states have enacted healthcare-specific “mini-HSR” laws that require parties to provide advance notice of material transactions to state attorney general offices or health departments. California’s Office of Health Care Affordability now requires 90-days’ notice before a wide range of healthcare transactions are entered into, including “mergers, acquisitions, corporate affiliations, or other transactions that entail a material change to ownership, operations, or governance structure involving health care service plans, health insurers, hospitals or hospital systems, physician organizations, providers, pharmacy benefit managers, and other health care entities.”¹⁹ Other states, including New York, Connecticut, Colorado, Oregon, and Washington, have implemented similar premerger notification regimes.²⁰ These laws permit state enforcers to intervene in deals that might otherwise evade, or clear, federal antitrust review.

Merger Enforcement. Cutting across industries, the states have shown a willingness to challenge mergers they view as anticompetitive. Eight states, joined by private plaintiff DirectTV, recently succeeded in obtaining a preliminary injunction of the merger of Nexstar and Tegna. They persuaded the court that the deal was likely to substantially lessen competition in the local television station market, despite the fact that the deal had received clearance from the DOJ and approval from the FCC.²¹ And thirteen states have banded together to challenge under the Tunney Act the settlement between the DOJ and HPE/Juniper, which allowed that deal to proceed.²²

The states have also expanded the merger-enforcement tools at their disposal. California, Colorado, and Washington recently enacted comprehensive, premerger notification regimes modeled on the federal Hart-Scott-Rodino Act.²³ Similar legislation is pending in other jurisdictions, including the District of Columbia, Hawaii, and West Virginia.²⁴ This is in addition to the health-care specific merger-review regimes certain states have enacted. Given this new raft of legislation, it is critically important that companies and their outside counsel be familiar with this patchwork of new requirements.

Criminal Antitrust Prosecutions. Ramped-up state antitrust enforcement is not limited to the civil context. Historically, the states have only rarely pursued criminal antitrust violations, but the tide is turning there, too. The Ohio State Attorney General’s office, for example, recently obtained an indictment against an individual accused of criminal bid rigging and is actively prosecuting the case.²⁵ That is not a one-off. Leaders in a variety of different state Attorney General offices, including New York and California, have publicly announced their intent to reinvigorate state criminal antitrust prosecution.²⁶

A number of states have amended—or are in the process of amending—their state antitrust laws to expand criminal penalties. California, for example, recently amended the Cartwright Act to enhance significantly criminal fines and prison terms for violations of the antitrust laws.²⁷ And New York is in the process of updating the Donnelly Act to do the same.²⁸

Companies ignore state enforcers at their peril. While certain types of companies (Big Tech, for example) have been in the states’ crosshairs for some time, the ESG antitrust enforcement examples demonstrate that conduct previously thought of as benign is beginning to attract the attention of state enforcers. Companies must evaluate their potential antitrust exposure at the state level and implement compliance programs that account for state priorities. Companies contemplating mergers must widen their aperture beyond federal clearance to encompass the new, and growing number of, state merger laws.

The O’Melveny team has deep expertise in antitrust litigation, merger clearance, and compliance programs and significant experience navigating complex state enforcement issues.