Brandon O'Neil


Brandon focuses on complex cross-border regulatory investigations, financial crime matters and litigation, with particular experience representing financial institutions.

He advises clients on a broad range of issues such as insider trading, anti-money laundering, asset tracing and judgment enforcement, fraud and bribery.

Brandon represents both institutions and individuals in cross-border investigations involving a range of regulators in the U.S. (DOJ, SEC, CFTC), Europe (UK FCA, SFO) and Asia. He has particular expertise in investigations involving insider trading, money laundering, market manipulation, bribery and fraud. In addition to England and Wales, Brandon is admitted to the Bar of the State of New York and worked for a number of years in the firm's New York office. Given the critical importance of U.S. law in contentious regulatory investigations and the far-reaching impact of U.S. authority-led investigations, this dual-experience brings valuable insight and experience to clients when they experience multi-jurisdictional, multi-agency investigations. Brandon also has substantial experience in submitting and defending private criminal complaints in continental European jurisdictions.

Brandon' s litigation practice focuses on cross-border fraud, asset tracing and judgment enforcement matters. Brandon' s dual New York and English qualification, together with his extensive experience litigating in various jurisdictions around the world, brings the cross-border outlook needed to successfully pursue (or defend) complex cases of this type. In addition to experience in such cases in the UK courts, Brandon has represented clients in numerous such enforcement cases across Europe, the U.S., the Caribbean and Asia, seeking to recover a broad range of assets ranging from art to real estate.


Representative matters

Lead associate in representation of Fabrice Tourre, Vice President of a multinational financial institution, in defense of SEC charges, and high–profile testimony before the U.S. Senate committee, alleging fraud in marketing a CDO tied to subprime mortgages. 

Represented major global financial institution in regulatory investigation by the SEC. 

Conducted an internal investigation on behalf of a major global corporation relating to insider trading allegations. 

Represented global corporation in Department of Justice and SEC fraud investigation. 

Represented individual employees of global corporation in joint CFTC and FSA investigation relating to market manipulation.



Admitted: Bar of the State of New York, 2009

Admitted: England & Wales, 2018


J.D., Columbia Law School, 2008

M.A., University of Wyoming, 2004

B.A., University of Wyoming, Phi Beta Kappa, 1999

A&O Shearman was formed on May 1, 2024 by the combination of Shearman & Sterling LLP and Allen & Overy LLP and their respective affiliates (the legacy firms). Any matters referred to above may include matters undertaken by one or more of the legacy firms rather than A&O Shearman.