Billy Marsh is a Partner at A&O Shearman who focuses on high-stakes litigation and investigations. He is regularly engaged by clients to handle their most significant legal disputes and has developed particular expertise in shareholder litigation, securities litigation and mass tort matters.
Billy has secured notable successes in complex and high-value disputes. He obtained a complete defense verdict following a two-week final arbitration hearing in a matter brought by a bankruptcy litigation trustee seeking more than USD 600 million in damages for alleged breaches of fiduciary duty. He also successfully defended Twitter in shareholder actions seeking to block Elon Musk’s USD 44 billion acquisition of the company.
In addition, Billy was recognized by The American Lawyer in its Litigator of the Week series for his representation of Dow Chemical in litigation brought by the State of Maine relating to alleged environmental contamination involving per- and polyfluoroalkyl substances (PFAS).
Billy received the 2025 Texas Outstanding Young Litigator Award from the Litigation Section of the State Bar of Texas. Clients commend him for being highly intelligent, practical, responsive and dependable in managing significant litigation matters.
- Class action
- Commercial
- Commercial and transactions
- Commercial disputes
- Dispute resolution
- Securities
- White collar crime
- Accounting
- Agriculture
- Aviation
- Automotive
- Banking
- Construction and materials
- Consumer goods and services
- Energy
- Financial services
- Fisheries and aquaculture
- Food and beverage
- Forestry
- Gaming
- Government and public policy
- Healthcare
- Industrials
- Insurance
- Investment management
- Media
- Mining
- Natural resources
- Oil and gas
- Pharmaceutical and life sciences
- Real estate
- Shipping
- Social infrastructure
- Technology and telecommunications
- Tourism
- Transport
- Utilities
- JD, University of Virginia - 2014
- Attorney-at-Law, State of Texas
- Registered Foreign Lawyer, England and Wales - 2024