Stacey Anne Mahoney
Stacey Anne Mahoney’s practice encompasses all aspects of antitrust law. In her antitrust litigation practice, she represents clients as plaintiffs and defendants in courts throughout the United States in cases involving restraints of trade, monopolization, price fixing, tying, exclusive dealing, price discrimination, false advertising, unfair competition, and related business torts. She has also litigated numerous complex commercial cases in federal and state courts across the country. In her merger practice, Stacey develops and implements domestic and international merger advocacy strategies, including trial as needed. Stacey’s counseling practice includes advising on distribution, employment, and pricing issues, as well as joint ventures and other competitor collaborations.
Stacey analyzes and designs antitrust compliance programs for domestic and international clients, and regularly represents clients before the US Department of Justice (DOJ), Federal Trade Commission (FTC), and states’ attorneys general in civil and criminal antitrust matters. She has worked extensively in pharmaceuticals and healthcare, payment systems, financial services, advertising and marketing, retail, and publishing.
Stacey is consistently ranked among the top antitrust lawyers in New York by Chambers USA and Super Lawyers, The Legal 500, and Global Competition Review. Chambers USA recognizes her “excellent antitrust litigation practice” and describes her as “very smart and very responsive,” and “very perceptive and very knowledgeable,” offering a “highly pragmatic approach to matters.” Super Lawyers reports that she is a “fearless and innovative litigator, able to adjust to any type of antitrust case,” who has “an outstanding ability to think strategically.” In 2019, Stacey was awarded the William T. Lifland Award bestowed in recognition of her role as a leading antitrust practitioner and her service to the broader antitrust community.
Stacey regularly writes and speaks on antitrust issues in the United States and abroad. She is a fellow of the Litigation Counsel of America and the American Bar Foundation. She is a past chair of the Antitrust and Trade Regulation Committee of the New York City Bar Association, and a former chair of the Antitrust Section of the New York State Bar Association.
Stacey clerked for Judge K. Michael Moore, now former-Chief Judge, in the US District Court for the Southern District of Florida from 1994 to 1996.
She serves on the Steering Committee for ML Women NY, is the co-chair of the ML First Generation Lawyers’ Network, was formerly the co-chair for the Morgan Lewis Return to Work Network, and was on the firmwide ML Women Steering Committee.
Antitrust and Commercial Litigation
- Lead Counsel representing a defendant in numerous antitrust class actions throughout the country in which plaintiffs are challenging the financial structure of the US residential real estate industry
- Lead Counsel representing a defendant brokerage in multiple antitrust class actions challenging the payment structures in the yacht industry, currently pending in the Southern District of Florida
- Lead Counsel representing treasuries platform defendants in In re Treasury Securities Auction Antitrust Litigation in multidistrict class action litigation, successfully obtaining dismissal of all claims in the Southern District of New York and the Second Circuit
- Lead Counsel representing Sun Pharmaceutical Industries in a Sherman Act Section 1 alleged reverse payment direct purchaser class action in the Southern District of New York, successfully obtaining dismissal of all claims
- Lead Counsel representing a utility in Section 1 and Section 2 purported exclusive dealing antitrust case in the Southern District of New York and Second Circuit Court of Appeals, successfully obtaining dismissal of all claims
- Lead Counsel representing ICAP Capital Markets and affiliates in a Sherman Act Section 1 regarding interest rate swaps in a multidistrict class action litigation consolidated in the Southern District of New York, successfully obtaining dismissal of all claims
- Lead Counsel representing two settlement federal antitrust and business tort cases simultaneously litigated in the District of Minnesota and the Southern District of New York on behalf of News America Marketing In-Store
- Lead Counsel representing City University of New York in a New York state court litigation, successfully defeating a New York Donnelly Act antitrust claim
- Lead Counsel representing News America Marketing FSI, successfully obtaining dismissal of antitrust claim in New York state court
- Lead Counsel representing Investor's Business Daily in various commercial litigations in federal and state courts, successfully resolving all claims on behalf of client
- Lead Counsel defending deceptive and unfair trade practices act class action in the Eastern District of New York, successfully resolving all claims on behalf of client
- Lead Counsel representing generic pharmaceutical company in In re Generic Pharmaceuticals Pricing Antitrust Litigation in multidistrict class action litigation pending in the Eastern District of Pennsylvania
- Lead Counsel representing medical device companies and their principals defending business tort claims in New York state court
- Trial Counsel representing CCC Holdings in a District of Columbia federal court antitrust merger preliminary injunction hearing
- Trial Counsel representing News America Marketing FSI in the Northern District of California and the Ninth Circuit Court of Appeals in a Sherman Act and California Cartwright Act antitrust and business tort litigation
- Represented defendant branded pharmaceutical company in an action brought by FTC and multiple state attorneys general alleging delayed generic competition as a result of restricted distribution and exclusive supply agreements pending in the Southern District of New York, resolving all claims on behalf of client
- Represented defendant generic pharmaceutical company in alleged direct and indirect purchaser reverse payment class actions consolidated into a multidistrict litigation in the Eastern District of Virginia
- Represented pharmaceutical companies in numerous state trial and appellate courts defending business tort claims
- Represented Travelport in an indirect purchaser antitrust class action regarding global distribution systems in the Southern District of New York, obtaining dismissal of all damages claims
- Represented Ranbaxy Pharmaceutical through appeal to the Second Circuit Court of Appeals, successfully obtaining dismissal of multiple reverse payment indirect purchaser class complaints
- Represented SanDisk in connection with antitrust claims directed to certain licensing conduct
- Represented Circuit City Stores in the Eastern Districts of New York and Tennessee in class actions alleging anticompetitive price overcharges
- Represented to settlement a plaintiff class of retailers against Visa and MasterCard in a federal antitrust tying case litigated in the Eastern District of New York, the Second Circuit Court of Appeals, and up to the US Supreme Court
- Represented to dismissal the National Fire Protection Association in a federal antitrust litigation in the District of Arizona
- Represented Coalition for a Democratic Workplace, National Federation of Independent Business Small Business Legal Center and Consumer Technology Association in amicus curiae submission to Ninth Circuit Court of Appeals in Chamber of Commerce of the United States of America v. City of Seattle, in an antitrust and labor law-based preemption challenge to City of Seattle Ordinance 124968
Transactional Antitrust and Agency Advocacy
- Lead Counsel representing various life sciences companies in ongoing federal and state investigations
- Lead Counsel representing various media companies in multiple FTC and DOJ antitrust and consumer protection investigations, successfully convincing the agencies not to pursue civil or criminal enforcement
- Lead Counsel representing a third-party retailer in the FTC investigation of the acquisition Prime Outlets Acquisition Co. by Simon Property Group, Inc.
- Represented Aurobindo Pharma in its acquisition of a portfolio of products from Spectrum Pharmaceuticals Inc. that was permitted to close without conditions
- Represented Japanese trading company in acquisition of US fencing manufacturer that was permitted to close without conditions
- Represented UBM plc in the sale of PR Newswire
- Represented Svenska Cellulosa Aktiebolaget SCA before US antitrust regulators in its approximately $513 million acquisition of Wausau Paper Corporation that was permitted to close without conditions
- Represented Ranbaxy Laboratories Limited before the Federal Trade Commission in its approximately $4 billion acquisition by Sun Pharmaceutical Industries Limited that was permitted to close with minimal divestiture
- Represented Nippon Yusen Kabushiki Kaisha before the European Union Competition Commission in its sale of a minority share in NYK Ports LLC to Macquarie Infrastructure Partners III, L.P. that was permitted to close without conditions
- Represented Baldor Electric Company before regulatory agencies in the United States, Austria, Brazil, Canada, Germany, and Italy in its approximately $4 billion acquisition by ABB Limited that was permitted to close without conditions
- Represented Schlumberger Limited before regulatory agencies in the United States, Argentina, Brazil, Canada, Colombia, the European Union, Mexico, and Russia in Schlumberger's approximately $11 billion merger with Smith International that was permitted to close without conditions
- Represented an oil field services company in various Department of Justice investigations in which the Department of Justice declined to pursue civil or criminal enforcement
Counseling
- Counseling domestic and international clients in numerous industries regarding distribution and pricing practices, antitrust compliance programs, potential mergers, joint ventures and other competitor collaborations and collective negotiations, including as impacted by recent guidance issued by domestic and international regulators
- Fordham University School of Law, 1994, J.D.
- University of Michigan, 1991, B.A.
- New York
- Supreme Court of the United States
- US Court of Appeals for the Second Circuit
- US District Court for the Eastern District of Michigan
- US District Court for the Eastern District of New York
- US District Court for the Southern District of New York
- Clerkship to now-Chief Judge K. Michael Moore of the US District Court for the Southern District of Florida (1994 - 1996)


Listed, Lawdragon 500, Leading Global Antitrust & Competition Lawyer, Commercial Litigation, Antitrust (2025)
Listed, Lawdragon 500, Leading Litigators in America, Antitrust Litigation (2022, 2024–2026)
Listed, The Best Lawyers in America, Antitrust Law, New York (2021–2026)
Member, Practice Group of the Year, Competition, Law360 (2017–2021)
New York State Bar Association
- Antitrust Committee: Executive Committee Member, former Chair
American Bar Association
- Section of Antitrust Law: member of Federal Civil Enforcement and Trial Practice Committees
- Liaison between Section of Antitrust Law and Section of International Law (2017–2018)
- Section of International Law: Vice Chair, International Antitrust Law Committee (2015–2018)
- Litigation Section: member of Women Advocate Committee
New York City Bar Association
- Antitrust and Trade Regulation Committee: Chair (2015–2018)
Women's Competition Network
Fellow, The American Bar Foundation (2016–present)
Fellow, Litigation Counsel of America (2015–present)
Recommended, Antitrust: Civil litigation/class actions: defense, The Legal 500 US (2020–2025)
Ranked, Antitrust, New York, Chambers USA (2010, 2013–2025)
Recognized, Litigation Star: Competition/antitrust, Benchmark Litigation (2022, 2024, 2025)
Recognized, William T. Lifland Award (2019)
Recognized, Metro Super Lawyers, Top 50 Women New York (2017–2022)
Recognized, US News & World Report and Best Lawyers 2017 Practice Group of the Year for Antitrust Law
Recognized, Super Lawyers, New York (2009–2024)
Recognized, Competition, Global Competition Review's Who's Who Legal (2015, 2018–2024)
Recognized, Irish Legal 100 (2015–2018); Antitrust Litigator of the Year: New York (2015)
Recognized, Legal 500 United States, Antitrust (2013–2015)
Recognized, LatinVex, Latin America's Top 50 Female Lawyers, only lawyer recognized for Litigation, Antitrust (2014)
2013 Law360 Competition Editorial Advisory Board
Recipient, 2016 Global Law Conference Antitrust Litigator of the Year
Recipient, Archibald R. Murray Public Service Award, Fordham University School of Law
Notes and Comments Editor, Environmental Law Journal, Fordham University School of Law
