We are Grant Thornton

Arlington, Virginia

  • Healthcare
  • Technology, media & telecommunications
Service Experience
  • Public Sector
  • Advisory
  • Audit & Assurance

Greg Wallig




Executive summary


Greg Wallig is the head of Public Policy, serving as the firm’s primary liaison with members of Congress, while also representing policy positions with standards-setters, regulators and other policymakers at all levels of government. Additionally, he is the firm’s MetroDC-Arlington market managing principal. The twin roles make him one of the firm’s leading faces to the Washington, D.C. market, representing Grant Thornton in the country’s fifth-largest economy.


Frequently named to the Virginia 500 Power List published by Virginia Business, Greg is a people-focused leader who believes deeply that diverse perspectives produce better outcomes. He has long championed Grant Thornton’s diversity, equity and inclusion efforts, and in 2021 was recognized as a national leader for his contributions as a diversity advocate in the Washington, D.C. region. 


Unique to Greg is his breadth of experience: he has worked across multiple industry segments, from technology, to public sector, financial services and healthcare, and his personal and professional experience spans five of the seven continents, with particular expertise working between the US, Europe and India. His professional acumen spans audit, investigations, analytics, business process improvement and technology innovation. This experience provides Greg a wide lens he uses to address his clients’ biggest challenges in a comprehensive way.

As a compliment to his leadership role at Grant Thornton, Greg also serves on the boards of the Greater Washington Board of Trade, Virginia Society of CPAs, the Rosslyn Business Improvement District, the Global Fund for Children, and the Masters of Science in Business Analytics at William & Mary.




Professional qualifications and memberships


  • Certified Information Systems Auditor (CISA)
  • Certified in the Governance of Enterprise Information Technology (CGEIT)
  • Information Systems Audit and Control Association (ISACA)
  • Virginia Society of CPAs, Board Member



Presentations and publications


  • Virginia Business magazine
  • Public Risk magazine
  • Congressional Roll Call
  • The Institute of Internal Auditors Research Foundation (IIARF)
  • Irish Times
  • Journal of Cost Management





  • MBA, Georgetown University (anticipated 2024)
  • BA, International Relations, William & Mary

Search for people at Grant Thornton


Enter a name and/or keywords such as service area, industry or location to get to know our business leaders — partner, principal or managing director. We look forward to hearing from you.