William B. Mack

William B. Mack


William B. Mack focuses his practice on government investigations and regulatory and compliance matters. He is also experienced in advising companies on regulatory and compliance matters relating to the Securities and Exchange Commission regulations, the Exchange Act, Anti-Money Laundering laws and Financial Industry Regulatory Authority (FINRA) rules.

Prior to joining the firm, William was a Principal Counsel for Enforcement at FINRA. Before FINRA, he was the Director of the Executive Secretariat in the Office of the U.S. Trade Representative. William also served as a Deputy Associate Counsel at the White House, advising primarily on appointments and investigations. Before the White House, he practiced at large firms in New York. William clerked for Judge Robert L. Carter in the Southern District of New York.


  • Government investigations
  • Government relations
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  • Principal Counsel, Financial Industry Regulatory Authority, Enforcement
  • Director, Executive Secretariat, Office of the U.S. Trade Representative
  • Deputy Associate Counsel, The White House

Recognition & Leadership

  • Listed, City & State’s "New York City 40 under 40 Rising Stars," 2015
  • Term Member, Council on Foreign Relations
  • Board of Directors, Hebrew Language Academy


  • J.D., Columbia Law School, 2003
    • Writing and Research Editor, Columbia Journal of Law and Social Problems
  • B.A., summa cum laude, State University of New York at Albany, 2000
  • Hon. Robert L. Carter, U.S. District Court for the Southern District of New York
  • New York
  • U.S. District Court for the Eastern District of New York
  • U.S. District Court for the Southern District of New York