Mariquita L. Barbieri

Mariquita L. Barbieri focuses her practice on tax, M&A, corporate law, corporate finance and securities, real estate investment trusts, management team buyouts, and family office and private investor matters. She helps clients manage complex transactions with clear planning, practical judgment, and strategies aimed at reducing tax risk while supporting long-term business value.

Mariquita earned her B.A. in English, summa cum laude, from Saint Louis University in 2000. She earned her J.D. from Saint Louis University School of Law in 2003. She later earned her LL.M. in Taxation from Washington University School of Law in 2007, building a strong foundation for tax-focused corporate work.

Mariquita has more than 20 years of experience leading mergers, acquisitions, divestitures, and related business transactions. Her work spans technology, health care, financial services, manufacturing, energy, retail, food and beverage, real estate and construction, transportation and logistics, and entertainment and media, giving clients guidance shaped by many industries and deal structures.

Mariquita brings a former corporate counsel background to her outside counsel role. She has advised on corporate matters, trade compliance, employment law, tax, M&A, intellectual property, trade secrets, licensing, and sales across North America, Europe, Asia-Pacific, and Latin America, helping businesses protect assets and move transactions forward with confidence.

Mariquita also assists companies with compliance, ethics, privacy, and regulatory matters involving the FDA, USDA, EPA, GDPR, export controls, anti-boycott rules, FCPA, product stewardship, and code of conduct issues. She has helped clients address data breach incidents, privacy inquiries, internal investigations, crisis response, and risk controls that support safer operations.

Mariquita has handled major tax and M&A matters, including private equity and venture capital investments, reorganizations under IRC Sections 355 and 368, Hart-Scott-Rodino filings, asset sales, stock purchases, and a $6.3 billion acquisition. Her work helps clients plan carefully, close deals, improve operations, and pursue growth in competitive markets.

Mariquita L. Barbieri has been recognized by The Best Lawyers in America (by BL Rankings) for Corporate Law, 2024-2026, and by Missouri & Kansas Super Lawyers (by Thomson Reuters) for Mergers & Acquisitions in 2021. She was also named 40 Under 40 by St. Louis Business Journal in 2018, Top 100 People to Know to Succeed in Business by Small Business Monthly in 2017, Top Small Business Lawyer by Small Business Monthly in 2016, and received the Leadership Award from Dupont Nutrition and Health in 2009.

Law Office Affiliations

• Partner, Thompson Coburn LLP
• Member, ​American Bar Association, Tax Section
• Member, The Illinois Bar
• Member, The Missouri Bar
• Member, Bar Association of Metropolitan St. Louis
• Member, International Association of Privacy Professionals, Certified Information Privacy Professional

Licensed State

• Illinois
• Missouri

Education

• Washington University School of Law
  Master of Laws (LLM)
• Saint Louis University School of Law
  Juris Doctor (JD)
• Saint Louis University
  Bachelor of Arts (BA)

Awards & Badges