Mary K. Treanor


Mary K. Treanor is an associate in the Litigation Department. She focuses her practice on white collar matters, complex commercial litigation, and agency investigations and enforcement actions. Mary represents corporations and individuals in SEC, CFTC, FERC, and FINRA investigations. She also conducts and provides advice relating to internal investigations ranging from potential Ponzi schemes to violations of company policies and procedures. Additionally, she advises and assists in training financial institutions on Bank Secrecy Act and Anti-Money Laundering compliance.

Mary also provides pre-indictment and post-indictment representation on securities fraud and other allegations. Additionally, she responds to subpoenas on behalf of companies and individuals.


Representative Matters

  • Second chairing a three-week federal jury trial concerning securities fraud, market manipulation, and obstruction of justice charges
  • Representing multiple national energy companies facing FERC enforcement actions and district court litigation related to alleged market manipulation violations
  • Representing a national bank in federal lawsuits alleging tort and Bank Secrecy Act violations

Professional Highlights

Pro Bono Experience

Mary maintains an active pro bono practice. She represents an individual previously sentenced to life without parole for first-degree murder as a juvenile in conjunction with his re-sentencing in state court. In addition, she represented a federal inmate in his motion to vacate his sentence arising from carjacking and other federal crimes. She successfully appealed to the Pennsylvania Superior Court a family court order unlawfully holding her client in contempt. She also has provided assistance on asylum cases and helped spearhead the creation and maintenance of a website targeting human trafficking and analyzing applicable laws in all 50 states.

Professional Activities

Member of Ballard Spahr's Hiring and Summer Associate Committees

Recognition & Accomplishments

The Best Lawyers in America, "Ones to Watch," Commercial Litigation (Philadelphia), 2022

Award Recipient for Best Oral Argument in Wiley Rutledge Moot Court Competition

Speaking Engagements


Co-author, "The Intersection of Money Laundering and Real Estate," 2020 Guide on AML by the International Comparative Legal Guides, May 2020 

Co-author, "Supreme Court Forecloses Reimbursement for Certain Internal Investigations Under Mandatory Victims Restitution Act," Law Journal Newsletters, November 2018



Washington University School of Law (J.D. 2014, cum laude)
Executive Notes and Projects Editor, Washington University Journal of Law and Policy

College of the Holy Cross (B.A. 2008)