A member of the firm’s Corporate Services practice group, Mark Stoneman facilitates the structuring, financing and completion of acquisitions, mergers, divestitures, joint ventures and partnerships. His background in accounting and finance helps him to ensure that the agreements related to these transactions are consistent with his client’s goals and expectations with respect to financial matters, which can be of critical importance in transactions of this nature.

For large, national and international, privately held businesses—often in the industrial, pharmaceutical or biotechnology industries—Mark brings a constructive and imaginative outlook to highly successful transactional combinations. He advises from front-end strategic planning to managing the deal process through favorable execution and closing. Mark’s acquisition experience extends to transactions where real estate is a primary or sole asset.

When counseling clients in the preparation and negotiation of agreements, Mark translates the goals of his clients into “plain English” documents, which can be both understood by the parties and respected by the courts. During the course of such efforts, he finds that he is frequently able to uncover and resolve potential conflicts before they progress to litigation. Not only does this help to avoid the prospect of costly disputes, but it can ensure that clients’ expectations with respect to the agreements will be met or exceeded.

Mark serves large, privately held companies and smaller startups as outsourced corporate counsel. He helps as an on-call resource with daily affairs or when things go awry.

Active in firm management, Mark is a member of the firm’s Executive and Pension Committees. He previously served on the firm’s Opinion and Compensation Committees, and was chair of the Pension and Hiring Committees. In addition, he served as leader of the Corporate Services practice group from 2018 to 2020.

Mark is a frequent author and speaker on transactional law matters with numerous presentations to business and legal groups.


  • University of Missouri-St. Louis  (M.Acc., 2002)
    • Accounting
    • Pacioli Award from Faculty, Recipient
  • University of Missouri School of Law  (J.D., 1996)
    • Order of the Coif
    • Missouri Law Review, Member
  • University of Missouri  (B.S., cum laude, 1993)


  • Missouri, 1996
  • Illinois, 1997

Professional Activities

  • The Missouri Bar (Business Law and Property Law Committees) 
  • Illinois State Bar Association 
  • American Bar Association (Business Law and Real Property Sections; Mergers and Acquisitions Committee Liaison) 
  • Armstrong Teasdale Executive Committee 
  • Armstrong Teasdale Pension Committee (Chair)

Charitable and Civic Involvement

  • Junior Achievement (Teaching Volunteer, Former Legal Division Roundtable Member)
  • Edgewood Children’s Center (Former Board Member and Trustee) 
  • United Way of Greater St. Louis (Former Employee Campaign Coordinator)
  • Metro Theater Company (Former Board Member, Board Development and Facilities Committees)


  • Missouri Lawyers Weekly Power List, Mergers & Acquisitions (2023)
  • The Best Lawyers in America®; Corporate Law, Mergers and Acquisitions Law (2013-present)
  • Chambers USA: America's Leading Lawyers for Business for Corporate Mergers & Acquisitions (multiple years)
  • Missouri/Kansas Super Lawyers® (2010-present); Super Lawyers®, Business Edition (2011-2014); Super Lawyers®, Rising Star (2008, 2013)
  • Named an "Up and Coming Lawyer" by Missouri Lawyers Weekly (2008)
  • AV® Peer Review Rated, Martindale-Hubbell
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