Established 1963

Guillaume Buell

Guillaume Buell
Contact Info
Office Tel:
+1 212.907.0873
New York
140 Broadway
New York, NY 10005
1 King William Street
London, EC4N 7AF United Kingdom

Guillaume Buell is a Partner in the New York and London offices of Labaton Keller Sucharow LLP.  He is an experienced and trusted advisor to a wide range of institutional investors in the United States, the United Kingdom, Canada, and Europe regarding global securities litigation, corporate governance matters, and shareholder rights.  His clients include pension funds, asset managers, insurance companies, and other sophisticated investors.  As part of the Firm’s Non-U.S. Securities Litigation Practice, which is one of the first of its kind, Guillaume serves as liaison counsel to institutional investors in select overseas matters. 

Guillaume has played an important role in cases against CVS Caremark, Uniti Group, Nu Skin Enterprises, Conduent,, Genworth Financial, Rent-A-Center, and Castlight Health, among others. Guillaume has been recognized by Lawdragon among the top “500 Global Plaintiff Lawyers” and as a “Next Generation Lawyer.”

Prior to joining Labaton Keller Sucharow, Guillaume was an attorney with Cahill Gordon & Reindel LLP in New York and Hicks Davis Wynn, P.C. in Houston, where he provided legal counsel to a wide range of Fortune 500 and other corporate clients in the aviation, construction, energy, financial, consumer, pharmaceutical, and insurance sectors in state and federal litigations, government investigations, and internal investigations.

Guillaume is an active member of the National Association of Public Pension Attorneys (NAPPA), where he serves as an appointed member of its Securities Litigation Committee, Fiduciary & Governance Committee, and the New Member Education Committee.  In addition, he is actively involved with the National Conference on Public Employee Retirement Systems, the Association of Canadian Pension Management, the Michigan Association of Public Employee Retirement Systems, the National Association of Shareholder and Consumer Attorneys, the International Foundation of Employee Benefit Plans, and the Georgia Association of Public Pension Trustees.

Guillaume received his Juris Doctor from Boston College Law School and was the recipient of the Boston College Law School Award for outstanding contributions to the law school community.  He was also a member of the National Environmental Law Moot Court Team, which advanced to the national quarterfinals and received best oralists recognition.  While in law school, Guillaume served for the Honorable Loretta A. Preska, United States District Court for the Southern District of New York, and later in the Government Bureau of the Attorney General of Massachusetts.  He received his Bachelor of Arts, cum laude with departmental honors, from Brandeis University.

Guillaume is fluent in French and conversant in German.  He is an Eagle Scout and actively involved in his hometown's local civic organizations.


2009, Massachusetts
2010, New York
2012, Texas
2014, Supreme Court of the United States

U.S. Court of Appeals
2013, Second Circuit
2016, First Circuit
2020, Ninth Circuit

U.S. District Court
2010, Southern District of New York
2010, Eastern District of New York
2012, Eastern District of Texas
2012, Southern District of Texas
2013, Northern District of Texas
2015, District of Massachusetts
2018, Western District of Texas
2018, District of Colorado