Sean R. O’Brien Managing Partner

New York, New York

917-207-7132

Education

New York University School of Law, New York, New York J.D. Magna Cum Laude - 1994
Honors: Order of the Coif
Law Review, Senior Note and Comment Editor
Harvard College, Cambridge, Massachusetts A.B. Cum Laude - 1989

Bar Admissions

New York
U.S. District Court Southern District of New York
U.S. District Court Eastern District of New York
U.S. Court of Appeals for the Second Circuit
U.S. Court of Appeals for the Fifth Circuit
U.S. Court of Appeals for the Eighth Circuit
U.S. Court of Appeals for the Ninth Circuit
U.S. Court of Appeals for the Tenth Circuit

Mr. O’Brien has successfully represented large and small businesses, as well as individuals affiliated with such entities, in a wide range of disputes and civil, regulatory, and criminal proceedings. Mr. O’Brien’s practice principally involves disputes arising out of complex financial transactions, shareholder and partnership disputes, and employment and trade secret disputes. Mr. O’Brien also regularly represents firms and individuals in the technology sector.

Following law school Mr. O’Brien clerked on the United States Court of Appeals for the Second Circuit, and then began his career at Sullivan & Cromwell LLP, where for one year he litigated and tried, as lead counsel, prisoner civil rights cases as the firm’s Pro Bono Fellow. Mr. O’Brien later practiced at Sullivan & Cromwell in the areas of securities and antitrust litigation, and was chosen to be a member of the trial team in the defense of the Department of Justice’s landmark case against Microsoft Corporation.

Prior to the founding of O’Brien LLP in 2011, Mr. O’Brien was a partner at a litigation boutique headed by Stanley S. Arkin, one of the nation’s foremost white-collar criminal defense attorneys.

At that firm, and since the founding of O’Brien LLP, Mr. O’Brien has successfully resolved complex civil litigation and regulatory defense and criminal matters at the trial and appellate levels, and in alternative dispute resolution fora around the country.

Notable Representations

Represented a hedge fund in a jury trial pursuing claims of fraud and breach of fiduciary duty against a well-known public REIT, obtaining a verdict of $12.7 million, including punitive damages, and dismissal of all claims asserted against the client.
Represented a multibillion-dollar hedge fund in a three-week jury trial, obtaining dismissal of all damage claims brought against the fund, and $3 million in damages and attorneys’ fees award in favor of the fund.
Represented an individual in an insider trading investigation commenced by the Department of Justice, resolving the matter with no charges being brought.
Represented a private investment firm and obtained the complete dismissal, following an arbitral hearing, of multi-million dollar claims based upon an alleged breach of a capital- raising agreement and related fraud.
Represented publicly-traded commercial bank as defendant in action involving alleged multi-million dollar fraud and fraudulent transfers, obtaining dismissal of all claims.
Represented a hedge fund in a litigation brought against a former employee who had disclosed confidential information of the firm and violated a non-disparagement agreement, obtaining an arbitral award in favor of the firm and substantial damages.
Represented a hedge fund in an investigation and civil action by the Securities & Exchange Commission involving allegations of insider trading, obtaining the dismissal of all claims.
Represented an investment bank in an action to recover a transaction fee, prevailing in all respects after multi-day arbitration.
Represented an individual in United States v. Stein, et al., the largest tax-shelter prosecution ever brought by the Department of Justice, obtaining dismissal of all claims based upon governmental interference with employer’s obligation to advance attorneys’ fees.
Represented the sole manager of a $1.3 billion hedge fund in dispute and action brought against him arising out of dissolution of fund, obtaining dismissal of all claims.
Represented a leading investment bank in action alleging breach of contract and fraud in connection with private securities offering, obtaining dismissal of all claims.
Represented Microsoft Corporation as member of trial team in United States v. Microsoft Corporation, an antitrust enforcement action brought by the Department of Justice.

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Published Works

“Defend Trade Secrets Act Provides Hedge Fund Managers With Protections for Proprietary Trading Technology and Other Trade Secrets,” The Hedge Fund Law Report, Vol. 9, No. 25 (June 23, 2016), by Sean R. O’Brien and A.J. Monaco.

“How Can Hedge Fund Managers Protect Themselves Against Trade Secret Claims?,” The Hedge Fund Law Report, Vol. 7, No. 19 (May 16, 2014), by Sean R. O’Brien, Sara A Welch and A.J. Monaco.

“Hedge Fund Incentive Compensation Not Subject to Wage Claim Under New York Labor Law,” The Hedge Fund Law Report, Vol. 7, No. 14 (April 11, 2014), by Sean R. O’Brien and Sara A. Welch.

“Recent Developments Affecting the Protection of Trade Secrets by Hedge Fund Managers,” The Hedge Fund Law Report, Vol. 6, No. 41 (Oct. 24, 2013), by Sean R. O’Brien and Sara A. Welch.

“Can Hedge Fund Managers Contract Out Of Default Fiduciary Duties When Drafting Delaware Hedge Fund and Management Company Documents?,” The Hedge Fund Law Report, Vol. 6, No. 14 (Apr. 4, 2013), by Sean R. O’Brien and Sara A. Welch.

“Computer Crime in New York Federal and State Courts,” The New York Law Journal (Nov. 1, 2012), by Sean R. O’Brien and Sara A. Welch.

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