Professional Biography

Sean T. Prosser Partner

  • San Diego

    D +1.858.720.5773

    F +1.858.720.5873

    San Diego

    11988 El Camino Real, Suite 350

    San Diego, CA


  • Los Angeles

    D +1.310.788.3344

    F +1.310.788.3399

    Los Angeles

    1888 Century Park East, Suite 1700

    Los Angeles, CA


  • San Francisco

    T +1.415.344.7000

    F +1.415.344.7050

  • Palo Alto

    T +1.650.838.4300

    F +1.650.838.4350



Sean Prosser, a former SEC enforcement attorney, leads Perkins Coie’s White Collar, Government Investigations and Securities Litigation practices in Southern California. With offices in San Diego and Los Angeles, Sean defends clients facing SEC investigations, DOJ investigations and grand jury proceedings, and other civil and criminal government and regulator investigations and enforcement proceedings. His clients include public and private companies, officers and directors, board committees, broker-dealers, banks, investment advisors, hedge funds, certified public accountants, individual stock traders and public officials.

With a particular practice depth defending clients in securities investigations and white collar actions initiated by regulatory authorities in Los Angeles, San Diego and throughout California, Sean regularly represents clients before the following agencies and regulators:

  • U.S. Securities and Exchange Commission (SEC) 
  • U.S. Department of Justice (DOJ)
  • Financial Industry Regulatory Authority (FINRA) 
  • NYSE, NASDAQ and other stock exchanges 
  • California Department of Corporations 
  • U.S. Department of the Treasury, including Financial Crimes Enforcement Network (FinCEN) and Office of Foreign Assets Control (OFAC)   
  • Public Company Accounting Oversight Board (PCAOB) 
  • Internal Revenue Service (IRS) 

Sean also has a significant securities litigation practice. He defends public companies and their executives facing shareholder lawsuits in state and federal courts across the country, including the Delaware Court of Chancery.

During the course of his career, Sean has represented such companies as: American Pacific Corporation; AML Communications; Ascend Communications; Cogent, Inc.;; Digital Lightwave; dj Orthopedics; Dura Pharmaceuticals; EEX Corp.; Gemstar-TV Guide International; Goya Foods; Kintera; Kratos Defense & Security Solutions; Ligand Pharmaceuticals; Mentor Corp.; Netlist; NETSOL Technologies; Mallinckrodt Pharmaceuticals; PepperBall Technologies; Schlotzsky’s; SoftBank Corp.; Steakhouse Partners; Unison Healthcare; Wireless Facilities; and others.

Sean is recognized by Best Lawyers in AmericaSuper Lawyers and The Legal 500. He also sits on the Board of Editors of The Corporate Counselor. Sean has written and spoken extensively about SEC enforcement and securities matters, with a focus on insider trading, anti-money laundering, derivative claims and mergers, and fiduciary duty issues.


Professional Recognition

  • Named the Best Lawyers "Lawyer of the Year" Securities Litigation, 2018, and “Lawyer of the Year” for Corporate Governance Law, 2016
  • Recognized by Best Lawyers in America for Securities Litigation, Mergers & Acquisitions Litigation, SEC Enforcement Litigation, and Corporate Compliance & Corporate Governance Law, 2010 - 2018
  • Listed in San Diego Super Lawyers, 2010 - 2017
  • Recommended by The Legal 500 for Merger Litigation, 2012 - 2014

Professional Leadership

  • Association for Securities and Exchange Commission Alumni (ASECA), Member
  • California Bar Association, Member
  • San Diego Bar Association, Member

Related Employment

  • Morrison & Foerster LLP, Partner, 2005 - 2014
  • Fish & Richardson P.C., Principal, 2003 - 2005
  • Brobeck, Phleger & Harrison, LLP, Attorney, 1995 - 2003
  • U.S. Securities and Exchange Commission, Office of Enforcement, Los Angeles, CA, Attorney
  • U.S. Securities and Exchange Commission, Office of Broker-Dealer Enforcement, New York, NY, Law Clerk





Areas of Focus

Bar and Court Admissions

  • California

  • U.S. Court of Appeals for the Ninth Circuit

  • U.S. Court of Appeals for the Eleventh Circuit

  • U.S. District Court for the Central District of California

  • U.S. District Court for the Southern District of California

  • U.S. District Court for the District of Colorado


  • New York Law School, J.D., 1992
  • The University of Pennsylvania, B.A., 1986


Best Lawyers Award Badge Best Lawyers Award Badge

Sean Prosser will be a panelist at Securities Enforcement Forum West in San Francisco, California on Wednesday, May 13, 2015.