William E. Mahoney Jr.

William Mahoney


Bill Mahoney is an accomplished trial attorney whose practice is focused on complex business litigation. For more than 25 years, Bill has represented businesses of all sizes in a wide variety of commercial litigation, including employment discrimination and sexual harassment matters, unfair competition and restrictive covenant claims, theft of trade secret claims, class actions, copyright infringement and intellectual property matters, and professional liability disputes. In particular, he has provided management-side counsel in connection with union campaigns and elections, negotiations of collective bargaining agreements, and defending against unfair labor practices charges before the NLRB. Bill has developed a robust practice in counseling businesses in employee-departure litigation, regularly seeking or defending against injunctions in both state and federal court.

For over two decades, Bill has also represented companies within the financial services industry. He has represented financial institutions such as brokerage firms, investment advisers and banks in all manner of disputes, including securities litigation and arbitration, and regulatory investigations and enforcement proceedings.

With a pragmatic, value-driven and results-oriented approach to dispute resolution and litigation, Bill has earned the respect of clients and adversaries alike.

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Representative Matters

  • advised one of the country’s largest veal and lamb processing companies in back-to-back union organizing campaigns, both of which resulted in the company winning the union election
  • successfully represented the same company when the union subsequently filed numerous unfair labor practices charges against the company, including the alleged wrongful termination of a pro-union employee; following a two-week hearing before the National Labor Relations Board all but the most trivial charges were dismissed, the employee termination was upheld, and the election results were confirmed
  • represented a brokerage firm in a $25 million auction-rate securities case in federal court, securing a favorable settlement shortly after the jury trial began
  • represented a leading global biotech company in an injunction action against a former high-level employee and the competing firm he joined after it was discovered that the employee had downloaded thousands of the company’s computer files; successfully obtained an injunction against the former employee and the competitor and subsequently negotiated a resolution under which the competitor terminated its employment relationship with the employee
  • obtained a multimillion-dollar award on behalf of a broker-dealer client against a competing firm for unfair competition
  • secured dismissal of a financial advisory firm’s lawsuit against a distressed debt investment firm, in which the plaintiff asserted claims of tortious interference with contract and unfair competition and sought a seven-figure fee
  • secured a jury verdict in favor of a national entertainment franchise in a premises liability matter, following a week-long trial in federal court
  • defended multiple age and religious discrimination claims by former employees against a brokerage firm both in federal court and arbitration, obtaining an award of attorney’s fees against the employee in one matter and securing a settlement in which another employee paid a significant amount to our client
  • represented a national bank in a class action arising out of a municipal debt issuance
  • defended a regional broker-dealer against claims brought by a former broker for fraudulent inducement and related torts
  • represented a national computer retailer in a contractual dispute with an Internet service provider that was seeking millions of dollars in damages
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Bar Admissions
  • Pennsylvania
Court Admissions
  • Pennsylvania Supreme Court
  • U.S. Court of Appeals for the Third Circuit
  • U.S. Court of Appeals for the Fourth Circuit
  • U.S. District Court for the Eastern District of Pennsylvania
  • U.S. District Court for the Middle District of Pennsylvania
  • J.D., magna cum laude, Temple University Beasley School of Law
  • M.A., University of Rochester
  • B.A., magna cum laude, La Salle University

  • American Bar Association
  • Board of Managers, Abington YMCA
  • Stradley Ronon Diversity Group

Speaking Engagements

  • Presenter, “After the Election: What to Expect from the New Administration in the Securities Field,” Securities Regulation Committee Meeting
  • Speaker, “The Importance of Expert Witness Research,” Litigation Summit, The Legal Intelligencer
  • Speaker, “FINRA Arbitrations: Tools & Practical Guide for 2016 and Beyond,” The Knowledge Group
  • Panelist, “The Litigation Summit,” The Legal Intelligencer

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  • Pennsylvania Super Lawyers
  • Abington YMCA, Volunteer of the Year
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In The Community

When not practicing law, Bill devotes his time to charitable organizations, having served in the past as the president of the board of directors of the Make-A-Wish Foundation of Philadelphia and Southeastern Pennsylvania.

Bill was named Abington YMCA’s Volunteer of the Year in 2014. He serves on the Board of Managers of the Abington YMCA – and was President of the Board from 2015 through 2018 – and received the award as a “Y Champion for Social Responsibility” based on his leadership of the Abington YMCA Annual giving campaign, among other contributions. The Abington YMCA is part of the Philadelphia Freedom Valley YMCA, which serves more than 140,000 members and 200,000 individuals each year – regardless of age, income or background – to nurture the potential of children and teens, improve the nation’s health and well-being, and provide opportunities to give back and support neighbors.

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