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Karen M. Lerner

Partner

  • New York
  • 250 Park Avenue
    Suite 820
    New York, NY 10177
  • 212.371.6600
Headshot photo of Karen M. Lerner
Biography
Karen M. Lerner is a partner in our New York office focused on antitrust and commodities litigation. 
Over the course of her career, Ms. Lerner has successfully litigated complex class actions that have recovered billions of dollars on behalf of institutional and individual plaintiffs. She has played important roles in several landmark antitrust cases and remains one of the few women ever appointed as Interim Co-Lead Class Counsel in a Commodity Exchange Act case. In addition to her litigation work, she also advises individuals, corporations, and nonprofits regarding business practices and corporate governance. In 2022, Ms. Lerner was named a Fellow of the American Bar Foundation, a global honorary society limited to one percent of lawyers licensed to practice in each jurisdiction.

Prior to joining KM, Ms. Lerner was of counsel at McDonough, Korn & Eichhorn, where she handled cases up to and including at trial.

Ms. Lerner is actively involved in promoting volunteerism in the legal community and through women’s organizations. She is an advocate for diversity and inclusion and is a member of Women Antitrust Plaintiffs’ Attorneys (WAPA), an organization for female attorneys who focus their legal practice on representing businesses injured by cartels or other anticompetitive activities. Finally, in addition to her legal practice and activities, Ms. Lerner has served as a member of the Board of Directors for several charitable organizations.  

 
  • The University at Albany, SUNY (B.A. summa cum laude, Phi Beta Kappa, 1988)
  • University of Pennsylvania School of Law (J.D. 1991)
  • The United States Supreme Court
  • United States Courts of Appeals for the Second and Third Circuits
  • United States Court of Appeals for the District of Columbia
  • United States District Courts for the Southern and Eastern Districts of New York
  • United States District Court for the District of New Jersey
  • New York State Bar
  • New Jersey State Bar
  • The District of Columbia Bar
National Law Journal Elite Women of the Plaintiffs Bar, 2022-2023
Top Rated Antitrust Litigation Attorney, Super Lawyers, 2021-2024
Top Women Attorneys in New York, Super Lawyers 2023-2024
New York Metro Super Lawyers, 2025
Honoree, Inaugural 40 Over 40 Award, Association of the Junior Leagues International (AJLI), 2025
Top Attorneys in the New York Metro Area, American Registry, 2021, 2024
Top Women Attorneys in the New York Metro Area, American Registry, 2022, 2025
Law360's Competition Editorial Advisory Board, 2022-2023
  • Chambers Spotlight 2024 award

Experience

Some of Ms. Lerner's antitrust and commodities experience includes:
  • Interim co-lead counsel of a class led by the New Mexico Office of the Attorney General, the New Mexico State Investment Council, the Public Employees Retirement Association of New Mexico, and the New Mexico Educational Retirement Board in In re Credit Default Swaps Auctions Litigation alleging that leading credit default swap (CDS) dealers took part in a more than decade-long, multibillion-dollar scheme to manipulate the benchmark prices used to value credit default swap contracts at settlement.
  • Court-appointed executive committee member and class counsel in In re Digital Advertising Antitrust Litigation, representing publishers alleging that Google monopolized and suppressed competition in online display advertising.
  • Representation of the exchange-based class in In re LIBOR-Based Financial Instruments Antitrust Litigation, an antitrust case alleging that defendant banks colluded to misreport and manipulate LIBOR.  The case resulted in settlements totaling $190.45 million, which combined represent the largest recovery in a “futures-only” commodities class action litigation.
  • Special fiduciary representation for the exchange-based class in In re Foreign Exchange Benchmark Rates Antitrust Litigation for a putative class of participants who traded futures and options in the FX market. The case has already resulted in partial settlements of more than $2.3 billion.
  • Counsel in the benchmark antitrust litigation In re Commodity Exchange, Inc., Gold Futures and Options Trading Litigation, on behalf of a putative class of gold derivative traders. The case has resulted in settlements of $152 million.
  • Selected by the Court as co-lead counsel in In re J.P. Morgan Treasury Futures Spoofing Litigation, alleging that defendants manipulated U.S. Treasury futures for more than a decade and that this conduct contributed to the bank’s recent $920 million settlement with the DOJ, CFTC, and SEC. The case has a putative settlement of $15.7 million.
  • Court-appointed executive committee member and class counsel in In re Cattle and Beef Antitrust Litigation, representing cattle producers and cattle futures traders. The suit alleges that the “Big 4” meatpacking firms conspired to suppress prices for fed cattle and manipulate live cattle futures and options prices. The case has already resulted in a $83.5 million settlement with one of the defendants.
  • Representation of exchange-based investors in Shak v. J.P. Morgan Chase & Co., alleging monopolization and manipulation of the silver futures market in violation of federal antitrust and commodity exchange laws. The parties successfully reached a private settlement. The case preceded a related Department of Justice criminal investigation into J.P. Morgan that remains ongoing.
  • Counsel in In re Deutsche Bank Spoofing Litigation on behalf of a putative class of investors alleging manipulation through “spoofing” of U.S. Treasury futures traded on the Chicago Board of Trade and Eurodollar futures traded on the Chicago Mercantile Exchange.
  • Court-appointed to the executive committee and class counsel in In re Bank of Nova Scotia Spoofing Litigation, alleging that defendants manipulated precious metals futures traded on the New York Mercantile Exchange and the Commodity Exchange, Inc. The case resulted in a settlement of $6.6 million.
  • Co-class counsel on behalf of a certified class of class of exchange-based investors in Dennis v. The Andersons, Inc. et al. alleging monopolization and manipulation of Chicago Board of Trade soft red winter wheat futures contracts in violation of federal antitrust and commodity exchange laws.
  • Court-appointed discovery committee co-chair in In re Effexor XR Antitrust Litigation for a putative class of direct purchasers of brand name and generic equivalents of extended-release venlafaxine hydrochloride capsules against drug manufacturers.  Among the claims, Defendants are alleged to have delayed market entry of generic versions and entered into reverse payment settlements.
  • Representation as sole lead counsel in In re North Sea Brent Crude Oil Futures Litigation.
 Some of Ms. Lerner's other relevant experience includes:
  • Representation of a whistleblower in Anonymous, et ano. v. Moody's Corporation, et al., No. 103997/2012 (Sup. Ct. N.Y. Cty. and First Dept.), alleging millions of dollars of tax fraud using a sham captive insurance company for over a decade regarding domestic and international transactions. The litigation settled for $8.5 million.
  • Maverick v. Valeant Pharmaceuticals International, Inc., alleging that Valeant materially misrepresented its business model, touting artificial and unsustainable growth that was enabled by the company’s deceptive and illegal conduct.
 

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