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Securities Enforcement & Litigation

Whether you are a public company, a fund, or an entity required to disclose financial information, Arnold & Porter's Securities Enforcement & Litigation attorneys have led marketing-leading corporations and the individuals at the helm in “bet-the-company” securities-related issues spanning litigation, enforcement, corporate governance, compliance counseling, and investigations. Our team is a one-stop shop for private companies and public issuers, financial institutions, life sciences  companies, start-ups and tech giants alike, and executives, boards of directors, and special committees – including those navigating the evolving securities impact and landscape around AI. Together, we carry forward a tradition of excellence that dates to the founding of our practice by one of the authors of the seminal SEC antifraud provision, Rule 10b-5.

  • Proactive Compliance Counseling: We provide public and private issuers, and boards of directors and board committees proactive compliance, risk management and due diligence advice, both before and after securities-related issues arise.

  • Deftly Navigating Internal and Governmental Investigations: Our team is skilled at navigating complex internal investigations and defending against inquiries by the SEC, DOJ, state Attorneys General, PCAOB, and FINRA, with a focus on mitigating enforcement and litigation risk.

  • Defending Securities Litigation: We defend the full spectrum of securities litigation – shareholder derivative suits, class actions, IPO, M&A, insider trading, and private equity disputes, through to insurance, professional liability, and clearing and brokerage matters, including actions by state Attorneys General.

“Arnold & Porter does a very good job of thinking five steps ahead. They’re responsive, responsible, and are strategic thinkers.” – (client) Chambers USA 2026
“Arnold & Porter provides one-stop-shop service to clients across a myriad of private securities class actions, as well as accompanying regulatory probes in tightly regulated sectors.” – Legal 500 United States 2025
Securities Enforcement & Litigation Practice Is Recognized by Chambers USA 2026
Chambers USA Top Ranked 2026 logo
“Arnold & Porter’s team masters not only the law and facts of a case but also establishes a deep understanding of the industry in which its clients operate.” – (client) Chambers USA 2026

Experience Highlights

  • National accounting firm in SEC and PCAOB investigations involving auditor independence, including the performance of nonaudit services for audit clients and accounting firm entity theories of liability.

  • JPMorgan Chase in winning two summary judgment motions and a post-trial Rule 50/59 motion in a Sarbanes-Oxley whistleblower action, representing the client from OSHA investigation through jury trial and two related Second Circuit appeals.

  • Software company in an SEC inquiry stemming from a cyberattack; secured no enforcement action after multiple attorney proffers to the SEC.

  • Special Committee of the Board of Directors of Western Union as independent counsel charged with reviewing and investigating shareholder demand letters alleging breaches of directors’ and officers’ duty to oversee anti-money laundering and fraud compliance related to the cross-border transfer of fund.

  • Coherus BioSciences in the strategic acquisition of Surface Oncology and in connection with threatened shareholder litigation concerning merger disclosures.

  • AIG affiliate in securing unanimous reversal and directed judgment in the Eigth Circuit, erasing a $25 million coverage award in an insurance dispute arising from an oil and gas well explosion in North Dakota.

  • Biotherapeutics public issuer in defending against multiple ongoing securities class actions and tag-along derivative suits regarding disclosures about ability to generate revenue and drive demand for cell therapies.

  • FirstEnergy in defending against ongoing securities class action arising out of passage of Ohio House Bill, where we represent former EVP and CLO.

  • National accounting firm in dismissing regulatory investigations by international authorities against all 25-plus individual subjects without charges.

  • Emergent BioSolutions in securing favorable settlement within coverage limits of securities class actions and derivative suits, and successful resolution of investigations by the DOJ, SEC, NYAG, and other regulators, where we represented former head of CDMO business unit.

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Recognition

  • Chambers Global
    Investigations & Enforcement (International & Cross-Border) (USA) (2021-2026)
  • Chambers USA
    Auditor & Accountant Liability (Nationwide) (2025-2026)
    Corporate Crime & Investigations: The Elite (Nationwide) (2015-2026)
    Financial Services Regulation: Banking (Enforcement & Investigations) (Nationwide) (2006-2026)
    Securities: Regulation: Enforcement (Nationwide) (2010-2023)
  • The Legal 500 US
    Securities Litigation: Defense (2014-2026)
    Insurance: Advice to Insurers (2024-2026)
    General Commercial Disputes (2015-2026)
  • BTI Consulting Group
    Class Action Powerhouses (2025-2026)
    Gen AI Litigation Leaders (2026)
    Intimidating Opponent in Litigation (2023-2026)
  • Best Law Firms Ranked by Best Lawyers
    Litigation – Securities (National) (2011-2024)
    Litigation – Securities (Washington, D.C.) (2011-2024)
    Litigation – Regulatory Enforcement (SEC, Telecom, Energy) (National) (2011-2024)