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Mark Sullivan




Executive summary

Mark Sullivan is Grant Thornton LLP’s Chicago office managing principal and a member of the firm’s Partnership Board. He also serves as the relationship partner for several of Grant Thornton’s most important clients. In this role, Sullivan ensures that he is readily available to key accounts, along with other Grant Thornton leaders. He also ensures that clients have access to the firm’s industry insights and materials, along with the most qualified resources and teams for their specific needs.

Sullivan has more than 30 years of experience working closely with legal counsel, compliance and ethics officers, audit committees, internal audit functions and various corporate departments – helping these parties develop procedures and manage intricate regulatory matters and corporate investigations. He also serves as the co-global leader of Grant Thornton’s Forensic Advisory Services practice. In this role, he helps expand Grant Thornton’s global services related to financial crimes, as well as its investigative and dispute offerings.

Sullivan has led investigations and anti-bribery and corruption matters in the Americas, Europe, Africa and Asia. Previously, Sullivan served as a managing director and national practice leader of the corporate loss prevention practice at a large corporate investigations and risk consulting firm. Prior to that, he was the loss prevention practice leader at a Big Four firm. Earlier in his career, he served as a partner in a regional consulting firm and senior consultant in the fraud and security practice at Arthur Andersen.


Professional qualifications and memberships

  • Center for Interviewing Standards and Assessment, Advisory Committee Member
  • National Immigrant Justice Center, Leadership Board Member
  • American Society for Industrial Security
  • Certified Fraud Examiner (CFE)
  • Certified Forensic Interviewer (CFI)
  • Certified Protection Professional (CPP)


Community involvement

  • Choose DuPage, Board Member
  • Union League Club of Chicago
  • World Business Chicago, Board Member



  • BS, Administration of Justice, Southern Illinois University


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