William Regner is a member of Debevoise’s Mergers & Acquisitions, Technology, Media & Telecommunications, Financial Institutions, Corporate Governance and Public Company Advisory Groups. He is a member of the firm’s Management Committee and previously served as Deputy Chair of the firm’s Corporate Department. He focuses on public company transactions and corporate governance matters and advises boards, special committees and senior management on governance issues, including activist challenges and risk management. He has experience across many industries but is particularly active in the TMT and asset management sectors. He also regularly represents investment banking firms in their roles as financial advisors in major transactions. Mr. Regner was recognized as a “Client Service All-Star” by BTI Consulting.

Mr. Regner is ranked as a leading M&A lawyer by Chambers Global (2025) and Chambers USA (2025), where clients note that he provides “the highest level of legal services to his clients” and brings “deep experience, commercial sense and a practical approach to legal issues and challenges.” He is said to have “great perspective and judgment,” and a “command of details and balanced view.” He receives further praise for his “outstanding technical knowledge and commercial awareness” and his ability to “[come] up with creative solutions.” Clients have also said that Mr. Regner “really commands a room but is also a very good listener” and has “superb negotiating and drafting” skills. He is also recommended for M&A Large Deals and Corporate Governance by The Legal 500 US (2025), where one client has declared that he is “the best attorney of all I have used in 50 years of business.” Other sources have described him as “thoughtful, smart and savvy” and lauded his delivery of “high-value and to-the-point advice.” He is also recognized by IFLR1000 (2024) as a leading M&A lawyer.

Mr. Regner is a member of the Corporate Laws Committee of the Business Law Section of the American Bar Association, which is the committee responsible for updates to the Model Business Corporation Act.