Attorney U. Seth Ottensoser

U. Seth Ottensoser

New York, New York

Seth Ottensoser concentrates on mass arbitration claims, merger and acquisition litigation, securities class actions and corporate litigation. He represents consumers, labor unions, public pension funds, and individual shareholders. Mr. Ottensoser was named a leading lawyer by Super Lawyers magazine in 2010, and 2013-2019 for his work in securities litigation. In addition, he was recommended in The Legal 500 in 2011-2012 and 2016-2017. In January 2020, Mr. Ottensoser guest lectured at Stanford Law School on “International Securities Litigation after Morrison.” He is also a frequent guest lecturer at Harvard Law School, lecturing most recently in January 2018 on “The Marsh Securities Litigation: a Case Study” and “Recent Developments in Delaware Appraisal and Merger and Acquisition Litigation,” in October 2017 on “Kinross: The Anatomy of a Securities Fraud Action,” in March 2017 on developments in Delaware litigation relating to statutory appraisal rights (at the 8th Annual Harvard Association for Law and Business Symposium), in January 2017 on “Recent Developments in Merger and Acquisition Litigation and Third Party Liability,” in January 2016 on “Discounted Cash Flow Analyses: The Wrong Inputs Can Lead To Catastrophe,” in February 2015 on “Investment Banking: The Critical Component in Merger and Acquisition Litigation,” in January 2014 on “Stock Valuation in the Context of Delaware Litigation and Appraisal Actions,” in January 2013 on the topic of “Valuation of Securities: The Devil Is In The Details,” in October 2010 on the topic of “Global v. Golden and Maric v. Plato: The Importance of Discounted Cash Flow Analyses in Delaware Litigation,” and, in September 2009 on the topic of “Merger Multiples in the Context of Delaware Litigation.” Mr. Ottensoser’s successful actions include: In re Marsh & McLennan Cos., Inc. Sec. Litig., No. 04-CV-8144 (CM) (S.D.N.Y.) ($400 million recovery); In re Freeport-McMoRan Copper & Gold, Inc. Derivative Litigation, C.A. No. 8110-VCN (Del. Ch.) ($154 million recovery, representing the second largest derivative settlement in Delaware); In re Ascent Entertainment Derivative Litigation, No. 17201-NC (Del. Ch.) ($40 million derivative settlement brought by activist shareholder relating to the sale of the Denver Nuggets and the Colorado Avalanche); In re UnitedGlobalCom Shareholders Litigation, No. 1012-N (Del. Ch.) ($25 million recovery in a going-private transaction); and City of Austin Police & Retirement Fund v. Kinross Gold Corp., No. 12-CV-1203 (PE) (S.D.N.Y.) (settlement of $33 million).

Practice Areas

  • Business Law
  • Mass Arbitration


  • Queens College, 1992
  • University of Southern California, 1995

Bar Admissions

  • New York State Bar, Second Department (1996)