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Kathleen S. McArthur


Kathleen S. McArthur

Washington, D.C. +1 202-956-7591 +1 202-956-7591 +1-202-293-6330+1-202-293-6330
New York +1 212-558-4321 +1 212-558-4321 +1 212-291-9458 +1 212-291-9458
[email protected]
Kathleen S. McArthur, co-head of S&C’s Securities & Commodities Investigations practice and the Firm’s Commodities, Futures and Derivatives practice, has advised some of the world’s biggest companies on major matters involving complex financial products and physical commodities, including enforcement inquiries, internal investigations and commercial litigation. Katy has a keen understanding of trading and markets that enables her to advocate effectively for clients facing even the most complex allegations of fraud or market manipulation, including proceedings brought by the CFTC, SEC, FERC and DOJ.

Ms. McArthur has been recognized by leading publications, including Chambers USA and as a “Rising Star” by New York Super Lawyers, Who’s Who Legal: Investigations 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. She is a native speaker of Spanish and also is fluent in Portuguese.


White-Collar and Regulatory Matters
  • HDR Global Trading Limited and certain of its affiliates in resolving a CFTC investigation of alleged registration and KYC/AML violations at BitMEX, one of the world’s largest digital currency derivatives trading platforms. The CFTC resolution was announced in coordination with resolution of a parallel investigation by FinCEN; the coordinated resolutions represent the largest-ever settlement for registration violations in the digital assets space.
  • JPMorgan in achieving resolutions with the DOJ, the CFTC and the SEC, resolving multi-year investigations into alleged “spoofing” by JPMorgan traders in the precious metals and U.S. treasuries markets, and manipulation of precious metals barrier options.
  • Scotiabank in obtaining global coordinated resolutions with the DOJ and CFTC resolving  investigations of spoofing involving precious metals futures contracts as well as alleged failures to provide pre-trade mid-market marks to swap counterparties and other swap dealer compliance issues.
  • Tower Research in connection with coordinated DOJ and CFTC resolutions relating to spoofing activity by three former Tower traders. In November 2019, Tower entered into a Deferred Prosecution Agreement relating to the traders’ activity and simultaneously settled a parallel CFTC investigation of the same activity.
  • ​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.
  • Major energy firm in connection with inquiries by the CFTC and other regulators relating to trading in physical energy products and related financial instruments.
  • Numerous companies in SEC and CFTC enforcement inquiries relating to digital assets.
  • 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.

Recent Speaking Engagements
  • Moderator for “Law & Compliance – Enforcement,” at Futures Industry Association Futures & Options Expo (November 15, 2022, Chicago, IL)
  • ​Panelist for “Containing Wildfires: Cross-Border Class Actions and Multijurisdictional Litigation,” at the American Bar Association Business Law Section Annual Meeting (September 15, 2022, Washington, D.C.)
  • Panelist for “FERC Enforcement and Regulatory Developments,” at Futures Industry Association FIA Forum: Commodities 2022 (June 22, 2022, Houston, TX)
  • Panelist for “Cooperation and Self Reporting – Do You Have the Right to Remain Silent,” at Futures Industry Association Law & Compliance Conference (April 27-29, 2022, Washington, D.C.)
  • Panelist for “Breaking News on Crypto and DeFi” at the American Bar Association Derivatives & Futures Law Committee Annual Winter Meeting (January 26-28, 2022)
  • Panelist for “Increasing ROI through Diversity on Wall Street,” at Women on Wall Street Virtual Summit (October 6, 2021)
  • Moderator for “Enforcement Trends,” at Futures Industry Association Law & Compliance (FIA L&C) Conference (April 28-30, 2021)
  • Panelist for “U.S. Anti-Corruption Enforcement,” at the International Chamber of Commerce, Mexico Chapter (March 3, 2021)
  • Panelist for “CCO Reports and Risk Management Programs,” at Futures Industry Association Law & Compliance (FIA L&C) Annual Conference (October 9, 2020) 
  • Day Chair, American Bar Association Derivatives and Futures Law Committee Annual Winter Meeting (January 23-25, 2020, Naples, FL)
  • Panelist for “Recent Trends in Foreign Corrupt Practices Enforcement in Commodity Markets,” FIA Law & Compliance Division webinar series (August 22, 2019)
  • Panelist for “True Detective: Audits, Inquiries & Investigations,” at Futures Industry Association Law & Compliance Annual Conference (May 2019, Washington, D.C.) 
  • Panelist for “Enforcement / Litigation Developments,” American Bar Association Derivatives and Futures Law Committee Winter Meeting (January 2019, Naples, FL)
  • Panelist for “Spoofing Enforcement – Recent Developments,” Practising Law Institute (June 2018)​

Rankings and Recognitions
  • Chambers Global (2022)
  • Chambers USA (2021–2022)​
  • Named to Global Investigation Review’s Women in Investigations survey (2021)
  • Who's Who Legal: Investigations (2020–2022)
  • 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