John J. Liolos is a partner in Sullivan & Cromwell’s Litigation Group and a member of the Firm’s Criminal Defense & Investigations Group. His practice focuses on white-collar criminal defense, regulatory enforcement, internal investigations and complex litigation.
A distinguished former federal prosecutor with significant trial and appellate experience, John has led matters involving securities and commodities fraud and manipulation, insider trading, healthcare and government program fraud, investment and cryptocurrency fraud, and public corruption and bribery.
From 2021 to 2026, John served as a trial attorney in the Market, Government & Consumer Fraud Unit of the Fraud Section of the U.S. Department of Justice’s Criminal Division. At the DOJ, John led numerous investigations, prosecutions, trials and appeals, including as first-chair in securing trial convictions of multiple defendants in an insider trading scheme led by a board director; as first-chair in securing the trial conviction of a physician for government program fraud, and successfully arguing and defending the appeal in the U.S. Court of Appeals for the Tenth Circuit; securing the trial convictions of two former executive-level traders for a futures manipulation (spoofing) scheme; and obtaining numerous additional convictions in cases involving securities fraud, cryptocurrency fraud, insider trading, and public corruption, among others. John was awarded the Assistant Attorney General’s Award for Distinguished Performance for obtaining a guilty plea in a commodities manipulation scheme prosecution.
John also worked frequently in parallel with the SEC, CFTC, FINRA and other regulatory institutions on complex multi-agency matters. He led multiple significant corporate resolutions resulting in over $500 million in total monetary amount. He is experienced in evaluating corporate compliance and surveillance programs, and overseeing corporate monitorship and reporting obligations.
Prior to his government service, John was an associate in S&C’s Litigation Group where he focused on complex investigations and litigation. Earlier in his career, John clerked for federal judges on both trial and appellate courts.
