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Sean T. Prosser

San Diego, (858) 720-7938
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Sean Prosser's practice focuses on all aspects of securities litigation. Mr. Prosser, a former SEC enforcement attorney, defends companies and their officers and directors, as well as public accounting firms and broker-dealers, in shareholder class action, derivative, and corporate control lawsuits, and in enforcement investigations and proceedings by the SEC, FINRA, stock exchanges, California Department of Corporations, DOJ, PCAOB and other regulatory agencies. He also represents companies, including special committees and audit committees, in connection with internal investigations.

During his career, Mr. Prosser has defended numerous public companies and their executives in federal securities class action and state derivative lawsuits. He has represented clients in a broad range of industries, including life sciences, financial services, computer software and hardware, medical devices, and consumer products.

Mr. Prosser is recommended by Legal 500 (2012-2013), and is recognized by Best Lawyers in America for his expertise in Securities Litigation, Mergers & Acquisitions Litigation, SEC Enforcement Litigation, and Corporate Compliance & Corporate Governance Law. He has been selected for inclusion in San Diego Super Lawyers for 2010-2014.

Mr. Prosser is a member of the Board of Editors for the Corporate Counselor and a member of the Association for Securities and Exchange Commission Alumni (ASECA). He is also a member of the California Bar Association and the San Diego Bar Association. He is admitted to practice in California, before the U.S. District Courts for the Central and Southern Districts of California, and before the U.S. Court of Appeal for the Ninth Circuit.

Mr. Prosser was the Executive Notes & Comments Editor for the New York Law School Journal of International and Comparative Law.

In re Sprint Merger Litigation
(Kansas District Court; U.S. District Court for the District of Kansas). Represented SoftBank Corporation in litigation that sought to prevent its $21.6 billion acquisition of a controlling interest in Sprint Nextel Corporation. Plaintiffs ultimately withdrew their request for a preliminary injunction after oral argument and then voluntarily dismissed their claims after the transaction closed.
In re Mentor Corp. Shareholder Litigation
(Santa Barbara Super. Ct.; State of Minnesota District Court, County of Hennepin). Represent Mentor Corporation and its directors in shareholder class actions arising from $1.1-billion acquisition by Johnson & Johnson. Successfully obtained orders denying motion for preliminary injunction in California action, and staying parallel Minnesota action. Won summary judgment in clients’ favor following discovery.
In re Netlist, Inc. Securities Litigation
Represented Netlist, Inc. and its officers and directors in connection with state and federal shareholder litigation.  Favorably settled following successful federal motions to dismiss.  2009 WL 1293690 (C.D. Cal. Apr. 17, 2009); 2008 WL 2356699 (C.D. Cal. May 30, 2008).
SEC v. R. Brooke Dunn, et al.
(D. Nevada) Represented former officer of public gaming company in enforcement action alleging insider trading based on non-public material information concerning company's financial performance.
In re Cogent, Inc. Shareholder Litigation
(Los Angeles Super. Ct.; C.D. Cal.; Delaware Chancery Court.)  Represented Cogent, Inc. and its directors in shareholder class action lawsuits filed in California state and federal courts and in Delaware Chancery Court arising from $943 million acquisition by 3M. Successfully defeated plaintiffs’ motion to enjoin transaction (No. 5780-VCP, 2010 WL 3894991 (Del. Ch. Oct. 5, 2010)) and obtained stay of parallel California lawsuit.