Noted by Chambers USA as “an established figure for both his commercial and securities litigation practices,” Marc J. Sonnenfeld defends class actions asserting violations of the federal securities laws, derivative cases, claims arising from mergers and acquisitions, and appraisal actions, as well as regulatory and enforcement proceedings. Marc has argued numerous successful motions to dismiss, including recent victories in the Sixth, Seventh, and Ninth Circuits, and been recognized for his extensive trial experience.
Marc leads the defense of putative securities class actions and derivative cases around the United States having won motions to dismiss (many of which he argued) in 13 cases since 2009. At the federal and state level, he has successfully defeated challenges to merger transactions collectively valued in excess of $10 billion. He advises boards and has been counsel to board committees.
Among his appellate victories are an issue of first impression under the federal securities laws addressed by the Ninth Circuit, Retail Wholesale & Department Store Union Local 338 Retirement Fund v. Hewlett-Packard Co. (9th Cir. 2017), and two seminal cases deciding corporate governance issues under Pennsylvania law, Cuker v. Mikalauskas (1997) (amicus curiae), and LeMenestrel v. Warden (2008) (appellee).
A fellow of the International Academy of Trial Lawyers and American College of Trial Lawyers, Marc’s trial and appellate experience includes cases involving shareholder issues, such as appraisal trials and a challenge to the sale of a business, as well as cases with commercial claims. One of Marc’s trials was featured in a trial practice book, Trying Cases to Win: Anatomy of a Trial by Herbert J. Stern and Stephen A. Saltzburg.
Marc was selected as an Acritas Star Lawyer as a result of an 18-month long survey of nearly 4,000 general counsel and other senior leaders at legal departments around the world. Marc was chosen as a 2013 “Client Service All-Star” by BTI Consulting Group, and as one of five attorneys named “Securities MVP” by Law360 in 2012. Marc has been named one of Philadelphia’s top business litigators in The Best Lawyers in America since 1997, being selected as a “Securities Lawyer of the Year” in 2013. He has been included by Philadelphia Magazine as one of the 100 “Pennsylvania Super Lawyers” and was named “The Securities King of Pennsylvania” by Super Lawyers Magazine (2016) in a cover story profile.
Marc is active in bar activities and was awarded the 2010 Wells Fargo Fidelity Award from the Philadelphia Bar Association for his work developing and maintaining the Commerce Court Program in the Philadelphia Court of Common Pleas. He has served as chair of the Philadelphia Bar’s board of governors and co-chair of its Business Court Task Force.
After graduation from law school, Marc served as a law clerk to Judge Joseph S. Lord III, then Chief Judge of the US District Court for the Eastern District of Pennsylvania.
Appellate Victories
Delaware Trial and Appeal
Recent Denial of Injuction
Motions To Dismiss Granted By Trial Courts
Other Case-Dispositive Motions Granted by Trial Courts
Member, Law Firm of the Year, Securities Regulation, US News/Best Lawyers – Best Law Firms (2019)
Band 1, Litigation: Securities, Pennsylvania, Chambers USA (2018–2020)
Band 1, Litigation: General Commercial, Pennsylvania, Chambers USA (2018–2020)
Lifetime Achievement Award, The Legal Intelligencer (2017)
Life Sciences Star, Non-IP Litigation and Enforcement, LMG Life Sciences Guide (2017–2020)
Local Litigation Star, Commercial Litigation and Securities (Pennsylvania), Benchmark Litigation (2008–2018)
Recognized, Acritas Star Lawyer (2017)
Ranked, Chambers USA: America's Leading Lawyers for Business (2003–2017)
Recommended, Dispute resolution: M&A litigation: defense, The Legal 500 US (2020)
Recommended, Dispute Resolution: Securities Litigation - Defense, The Legal 500 US (2016-2019)
Recommended, Antitrust: Cartel and Antitrust - Civil Litigation/Class Actions, The Legal 500 US (2015)
Recommended, Litigation: Securities - Shareholder Litigation, The Legal 500 US (2014, 2015)
Recommended, Litigation, The Legal 500 US (2007)
Lawyer of the Year, Litigation – Securities, Philadelphia, The Best Lawyers in America (2013, 2019, 2020)
Lawyer of the Year, Antitrust Law, Philadelphia, The Best Lawyers in America (2020)
Recognized, Antitrust Law, Litigation: Securities, The Best Lawyers in America (2016–2019)
Recognized, Antitrust, The Best Lawyers in America (1995–2011)
Top 10, Pennsylvania Super Lawyers (2015)
Client Service All-Star, BTI Consulting Group (2013)
Securities MVP, Law360 (2012)
Recognized, Top 100 Philadelphia Lawyers
Recognized, Dispute Resolution, PLC Which Lawyer? Yearbook 2008
Wells Fargo Fidelity Award (2010)
Former President, Harvard Law School Association of Philadelphia
Joseph B. Shane Award, Swarthmore College
Fellow, American College of Trial Lawyers
Fellow, International Academy of Trial Lawyers
Copyright © 2021 Morgan, Lewis & Bockius LLP. All rights reserved.