Chicago 312-214-7900 | Cleveland 440-953-8888 | Birmingham 205-855-5700 | Detroit 313-488-0144 | New York 646-933-1000 | St. Louis 314-332-1500 | Washington, DC 202-975-2288

Mark S. Hamill

Mark represents plaintiffs in all aspects of direct and class actions in commercial, antitrust, securities, and consumer cases.

Contact Information

Mark concentrates his practice on commercial, antitrust, securities and consumer cases, often taking a lead role with expert witnesses in finance, accounting, and economics topics. He also serves as eDiscovery counsel in many of his cases, leveraging his depth of experience in this area as an attorney and as an eDiscovery project manager serving Fortune 500 and major accounting firm clients in large-scale, high-intensity projects.

Prior to joining the firm, Mark represented Direct Action Purchaser plaintiffs in antitrust cases, advancing their interests and coordinating with counsel in parallel actions.  He also represented shareholders in securities class actions at a securities boutique firm in New York, which included a Chinese reverse merger case where his deposition and class certification work were instrumental to achieving a favorable settlement for the class.

Before taking on eDiscovery projects and plaintiff representations, Mark practiced law with some of Chicago’s most prominent firms, where he served on trial and arbitration hearing teams in antitrust and accounting cases. He also represented clients in litigations and investigations involving commercial, securities, FCPA, and white-collar matters, including an insurance dispute arising from the Enron fraud and an internal investigation stemming from the Parmalat fraud.

Mark worked as a CPA and consultant with KPMG and Deloitte, and as a senior internal auditor at Whirlpool Corporation before attending law school. His volunteer work includes tax preparation for low-income individuals. He is also a non-combat veteran of the U.S. Army, where his assignments included serving in a multinational peacekeeping force in Sinai, Egypt.


  • American Bar Association
  • Illinois State Bar Association
  • Chicago Bar Association
  • American Institute of Certified Public Accountants

Practice Areas

  • Antitrust Litigation
  • Appellate Litigation
  • Class Actions
  • Commercial Litigation
  • Securities Litigation


  • Northwestern University Law School, J.D., cum laude
  • Washington & Jefferson College, B.A.

Bar Admissions

  • Illinois
  • New York

Court Admissions

  • United States Courts of Appeals, First Circuit
  • United States Courts of Appeals, Sixth Circuit
  • United States District Court, Northern District of Illinois

Tiffany R. Wunderlin