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Kathleen S. McArthur


Kathleen S. McArthur

New York +1-212-558-4321 +1-212-558-4321 +1-212-558-3588+1-212-558-3588
[email protected]
Kathleen McArthur is partner in the Firm’s Litigation Group and co-head of the Firm’s Commodities, Futures and Derivatives practice. Her practice focuses on regulatory enforcement proceedings, internal investigations and complex commercial litigation. She has represented companies in connection with internal investigations and a wide range of inquiries by the U.S. Commodity Futures Trading Commission, the U.S. Securities and Exchange Commission, the Federal Energy Regulatory Commission and the U.S. Department of Justice, as well as in inquiries by the CME, ICE and other exchanges and self-regulatory organizations. Ms. McArthur also represents companies in complex civil litigation, including securities class actions, shareholder derivative litigation and other commercial disputes.

Ms. McArthur has been recognized by leading publications, including as a “Rising Star” by New York Super Lawyers and by The Legal 500 United States, and is a Fellow of the Leadership Council on Legal Diversity. She also was a member of the Sullivan & Cromwell team that was awarded The Legal Aid Society’s 2018 Pro Bono Publico Award. Internally, Ms. McArthur serves as co-chair of Sullivan & Cromwell’s Women’s Initiative Committee. She is a native speaker of Spanish and also is fluent in Portuguese.


White-collar and Regulatory Matters
  • A financial institution in a multi-year investigation by the SEC regarding alleged manipulative trading, with the SEC issuing a non-public declination letter.
  • A financial institution in an internal investigation and regulatory inquiries involving alleged manipulation in precious metals markets, with the regulators taking no action.
  • Barclays in the investigation and resolution with the DOJ, CFTC, the U.K. FCA, and other regulators of matters relating to voice and electronic trading in the global FX Spot Market.
  • Numerous trading organizations in connection with inquiries by the CFTC regarding alleged spoofing or other disruptive trading conduct.
  • Major energy firm in connection with inquiries by the CFTC and other regulators relating to trading in physical products and related financial instruments.
  • Numerous trading organizations in connection with inquiries by the CFTC involving alleged manipulation of futures contracts for various agricultural commodities.
  • Numerous  financial institutions and trading organizations in connection with inquiries by the SEC and CFTC relating to the equity market “flash crash.”
  • Numerous financial institutions in investigations by FINRA, the NFA and other self-regulatory organizations.

Civil Matters
  • Barclays in multi-district litigation brought by major pension funds and institutional investors alleging banks violated antitrust laws by colluding to rig the $13 trillion market for Treasury securities.
  • Major manufacturer of building materials in a multidistrict and class action litigation, in connection with an alleged product defect and consumer fraud.
  • 18 of the world’s largest financial institutions in fraudulent conveyance and Article 78 actions against the New York State Insurance Department and the bond insurer MBIA Inc. and its subsidiaries challenging their $5 billion restructuring during the financial crisis.
  • UBS in securities class action and shareholder derivative litigation arising out of the accounting fraud of former UBS investment banking client HealthSouth Corp.
  • An investment bank in connection with fraudulent conveyance claims brought by liquidators of a Cayman hedge fund.
  • Major automotive manufacturer in connection with breach of contract claims against one of its suppliers.

Rankings and Recognitions
  • Who's Who Legal: Investigations (2020)
  • The Legal 500 United States (2018)
  • New York Super Lawyers "Rising Star" (2014–2018)
  • Fellow of the Leadership Council on Legal Diversity
  • Recognized as a member of the Sullivan & Cromwell team awarded The Legal Aid Society’s 2018 Pro Bono Publico Award