Sean Hennessy - McDermott Will & Emery


Sean Hennessy focuses his practice on white-collar and securities defense matters, including the defense of criminal and civil investigations brought by the Department of Justice (DOJ), the Securities and Exchange Commission (SEC), and State Attorneys General. Sean defends individuals and public and private companies against governmental investigations involving allegations of antitrust violations, securities and investment adviser fraud, insider trading, financial market manipulation, tax crimes and violations of the False Claim Act.

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  • Represents senior management of PG&E Corporation in shareholder derivative litigation arising out of the San Bruno pipeline rupture
  • Conducted an internal investigation of a REIT in response to an SEC investigation in which the SEC terminated its investigation subsequent to McDermott’s presentation of its findings
  • Conducted an internal investigation involving banking compliance issues and reported to the Chairman and CEO of the bank


The Best Lawyers in America, “Ones to Watch” in Criminal Defense: White-Collar, 2023


Loyola University of Chicago School of Law, JD, magna cum laude, 2013
University of Illinois at Urbana-Champaign, BA, 2010


US District Court for the Northern District of Illinois
US Court of Appeals for the Seventh Circuit