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    Home /  Lawyers /  Kathleen S. McArthur

    Kathleen S. McArthur

    Partner

    Washington, D.C. +1-202-956-7591
    New York +1-212-558-4321
    mcarthurk@sullcrom.com
    Kathleen S. McArthur Headshot Photo

    Washington, D.C.

    +1-202-956-7591

    New York

    +1-212-558-4321

    |

    mcarthurk@sullcrom.com

    Email vCard

    Kathleen S. McArthur is Co-Head of the Firm’s Securities & Commodities Investigations Practice as well as its Commodities, Futures and Derivatives Practice. She 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 and arbitration.

    Katy’s clients include a broad array of global financial institutions, investment managers, proprietary trading firms, and derivatives end users. Her keen understanding of trading and markets enables her to advocate effectively for clients facing even the most complex allegations of fraud or market manipulation, and she regularly advises clients in connection with enforcement inquiries by the CFTC, SEC, FERC and DOJ, as well as other federal and state regulatory agencies and self-regulatory organizations.

    Ms. McArthur also represents clients in litigation, including defending litigated enforcement matters as well as private litigation involving securities class actions, private actions alleging violations of the Commodity Exchange Act or antitrust law, shareholder derivative litigation and other commercial disputes relating to alleged product defects, consumer and accounting fraud, and breaches of contracts.

    A native speaker of Spanish and also fluent in Portuguese, Katy frequently advises companies throughout Latin America in connection with litigation and arbitration matters, as well as investigations and enforcement matters involving U.S. law, including matters involving allegations of fraud, market manipulation, bribery and corruption, accounting irregularities, and anti-competitive conduct, among other areas. She has extensive experience advising companies in the U.S. and abroad regarding U.S. enforcement authorities’ expectations for corporate compliance programs.

    She has been recognized by leading publications, including Chambers USA and The Best Lawyers in America. She has also been recognized 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.

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    Spotlight

    S&C Obtains Second Circuit Win for Barclays and Goldman Sachs in Treasury Auctions Antitrust Case

    Read More

    S&C Obtains Dismissals for Barclays in VIX Litigation

    Read more

    Practical Considerations for Achieving Global Resolutions in Cross-Border Investigations

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    • Experience
    • Rankings and Recognitions
    • News
    • Publications, Videos and Podcasts
    • Credentials
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    Experience

    Experience

    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

    • Chair and featured speaker for Sullivan and Cromwell’s Twentieth Annual Commodities and Derivatives Trading Seminar (November 10-12, 2025, New York and Houston)
    • Moderator for “CFTC and FERC Enforcement,” at Futures Industry Association’s Commodities Conference (October 6-8, 2025, Houston, TX)
    • Moderator for “Exchange and SRO Enforcement: Process and Trends,” at Futures Industry Association Law & Compliance Conference (April 23, 2025)
    • Panelist for “Defenders Panel,” at the Energy Bar Association’s Enforcers and Defenders Forum (April 2, 2025)
    • Moderator for “Enforcement to (Plenary),” at the American Bar Association Derivatives and Futures Law Committee Annual Winter Meeting (January 30-February 1, 2025, Naples, FL)
    • Moderator for “Enforcement: A Look Back and Forward,” at Futures Industry Association Law & Compliance Conference (April 24, 2024)
    • Panelist for “MNPI, Misuse of Confidential Information, and Physical Commodities Markets: Insights and Implications from Recent Enforcement Actions,” Futures Industry Association webinar (February 29, 2024)
    • Co-chair and Panelist for “Enforcement 2,” at the American Bar Association Derivatives and Futures Law Committee Annual Winter Meeting (January 25-27, 2024, Naples, FL)
    • Panelist for “Enforcement Cases,” at FIA Forum: Commodities 2023 (September 13, 2023, Houston, TX)
    • Panelist for “Crypto Regulation & Enforcement,” at Futures Industry Association Law & Compliance Conference (April 28, 2023)
    • Co-chair, American Bar Association Derivatives and Futures Law Committee Annual Winter Meeting (February 2-4, 2023, Hilton Head Island, SC)
    • 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 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,” Women on Wall Street Virtual Summit (October 6, 2021)
    • Moderator for “Enforcement Trends,” at Futures Industry Association Law & Compliance 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 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,” at 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,” at the 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)
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    Rankings and Recognitions

    Rankings and Recognitions

    • Chambers Global (2022–2025)
    • The Best Lawyers in America (2024)
    • Chambers USA (2021–2025)
    • Lawdragon “500 Leading Litigators in America” (2024–2026)
    • Named to Global Investigation Review’s Women in Investigations survey (2021)
    • Who’s Who Legal: Investigations (2020–2025)
    • 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
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    News

    News

    • S&C Obtains Second Circuit Win for Barclays and Goldman Sachs in Treasury Auctions Antitrust Case

      February 6, 2024
    • Jamie McDonald, Katy McArthur and Colin Lloyd Comment on CFTC’s New Enforcement Advisory with NYU Law’s Compliance & Enforcement Blog

      November 15, 2023
    • S&C Obtains Dismissals for Barclays in VIX Litigation

      October 13, 2023
    • S&C Clients Obtain Dismissal of Antitrust Claims Against Banks Over Treasury Products

      April 9, 2021
    • Katy McArthur Speaks at FIA Law & Compliance Division Conference

      April 28–30, 2021
    • S&C Hosts 16th Annual Commodities and Derivatives Trading Seminar

      April 8, 2021
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    Publications, Videos and Podcasts

    Publications, Videos and Podcasts

    • S&C Lawyers Contribute to Latin Lawyer: The Guide to Corporate Crisis Management, Fifth Edition

      Books February 1, 2024
    • ESG Trends and Hot Topics

      Newsletters May 31, 2022
    • U.S. Sanctions Considerations for Virtual Currency Industry

      Podcasts April 6, 2022
    • Latin Lawyer: The Guide to Corporate Crisis Management, Fourth Edition

      Books December 15, 2021
    • S&C Lawyers Author Law360 Article on Expectations for CFTC Enforcement

      Articles May 17, 2021
    • CFTC Releases New Guidance on Civil Monetary Penalties

      Podcasts June 22, 2020
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    Credentials

    Credentials

    Education

    • Harvard Law School, J.D., 2007
    • The University of Texas, B.B.A., 2002

    Bar Admissions

    • District of Columbia
    • New York

    Languages

    • Portuguese
    • Spanish
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    Related Practices

    Related Practices

    • Litigation
    • Commodities, Futures & Derivatives
    • Criminal Defense & Investigations
    • Digital Assets
    • Financial Services Investigations & Litigation
    • Latin America
    • Securities & Commodities Investigations
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