Stephen J. Kastenberg

Partner

Philadelphia

Tel 215.864.8122
Fax 215.864.9751

Stephen J. Kastenberg focuses on complex business litigation with an emphasis on antitrust and competition, securities, and corporate governance litigation. He has successfully defended public and private companies and universities in federal and state lawsuits, including class actions, throughout the United States. He also regularly represents clients as plaintiffs in business disputes, or assists them through internal investigations. Stephen is based in Philadelphia and is a member of the firm’s Senior Leadership Team. He serves as Legal Counsel to the Chair and Board and is a member of the firm's Executive Team.

In his nearly 30 years of litigation experience, Stephen has achieved a significant number of victories through trial, arbitration, summary judgment, advantageous settlement, and on appeal. His clients range from Fortune 100 multinational corporations to privately held companies and nonprofit organizations, and span such industry sectors as pharmaceuticals, chemicals, investments, media and technology, real estate, financial services, and higher education.

Services

Experience

Representative Matters

Nasdaq, Inc. v. Exchange Traded Managers Group et al.: lead counsel in securities contract dispute that resulted in judgment in favor of client of more than $80 million. See Nasdaq, Inc. v. Exchange Traded Managers Group et al., No. 17 civ. 8252, 2019 U.S. Dist. Lexis 220135 (S.D.N.Y. Dec. 20, 2019)
Served as lead counsel for NASDAQ OMX Group in numerous claims and regulatory matters arising from the commencement of trading of stock during the Facebook IPO; obtained an injunction against an exchange member seeking to assert substantial claims in arbitration against NASDAQ.
Served recently as lead counsel in defending a global pharmaceutical company in two unrelated 10-figure civil antitrust cases class actions asserting claims for monopolization and collusive dealing. In one matter, obtained summary judgment, affirmed on appeal, and decertification of an indirect purchaser class. In the second, resolved the case on terms favorable to the client after reducing the indirect purchase class from 50 states to four.

Represented corporate client in bringing and defending Lanham Act claims against or by competitors, seeking and defending against emergency injunctions and damages claims. Recent cases have involved billions of sales dollars. In one recent case, obtained a $50 million recovery for a client, mid-discovery.
Regularly represents companies and entrepreneurs in government and internal investigations; matters arising from derivative demand letters by shareholders; and in ownership disputes within closely held companies
Defended a Fortune 100 chemical manufacturing company against claims of more than $425 million by a purchaser, which arose from alleged fraud and breaches of purchase representations. Obtained a complete defense verdict at trial, affirmed on appeal to the Delaware State Supreme Court.
Led the defense of a real estate investment fund in the Florida federal and state courts in two class actions seeking hundreds of millions of dollars in damages, as well as in related individual actions asserting RICO and other violations. The claims were brought by thousands of property owners arising out of investments in 13 resort development projects. Obtained dismissal of the first class action, dismissal of two amended complaints in the second class action, and dismissal of three of the individual actions. None of the matters have resulted in adverse judgments.
Represented one of the world’s leading research universities in successfully defending against Title IX, contract, and related claims by students or faculty, including defeating two preliminary injunctions
Represents colleges and universities against claims, or anticipated claims, for reimbursement of tuition resulting from the need to implement remote learning curricula during the COVID-19 pandemic
Represented a global chemical company in a civil antitrust lawsuit in Colorado, where the company and a co-defendant were accused of conspiring to eliminate the plaintiff as a competitor in the auto refinishing market. Obtained summary judgment.
Represented a leading provider of cable, internet, and telephone services in a matter involving misappropriation of intellectual property. Resolved with the full return of all intellectual property at issue.
Represents public clients and board special litigation committees in derivative action litigation brought by stockholders, and advises clients in response to derivative action demand letters and other shareholder demands
Represented the estate of late rap musician Tupac Shakur and its co-administrator in two related defamation lawsuits arising from the lyrics of two songs on a Shakur platinum album. Obtained summary judgment in both cases and affirmance by the Third Circuit in the one matter proceeding through appeal.

Professional Highlights

Judicial Clerkships

Hon. Bailey Aldrich, U.S. Court of Appeals for the First Circuit, 1992-1993

Professional Activities

American Bar Association, Antitrust Section

New Jersey State Bar Association

Pennsylvania Bar Association

Philadelphia Bar Association

Ballard Spahr's Pro Bono Committee

Recognition & Accomplishments

The Legal 500 US, Antitrust - Civil litigation/class action - defense, 2019-2024; Antitrust - Civil litigation/class action - plaintiff, 2019, 2020

Chambers USA, antitrust, litigation: general commercial law (Pennsylvania), 2007-2024

The Best Lawyers in America, commercial litigation, 2012-2025; securities litigation, 2012-2024; "Lawyer of the Year," Litigation - Securities (Philadelphia), 2020

Speaking Engagements

"Ascertaining Ascertainability," HarrisMartin's Antitrust Pay-for-Delay Litigation Conference, Philadelphia, PA, September 10, 2015

Faculty, HarrisMartin's Antitrust Pay-for-Delay Litigation CLE Conference, Philadelphia, September 22, 2014

Board Memberships & Community Service

New Jersey Scholars Program, Member and past President

Lawyers' Committee for Civil Rights, Director and Trustee

Police Corruption Task Force, past appointee by Philadelphia Mayor Edward Rendell

Publications

Co-author, "NCAA Scores Key Victory in Case Involving Paying Student Athletes," Philadelphia Business Journal, October 5, 2015

Co-author, "The Corporate Antitrust Policy—Privileged or Not?" Law360, November 7, 2014

Co-author, "Landmark Lawsuit Shapes NCAA and the Future of Student-Athlete Compensation," Philadelphia Business Journal, August 19, 2014

Related Insights

Credentials

Education

Harvard Law School (J.D., cum laude, 1992)
Managing Editor, Harvard Journal on Legislation

Princeton University (A.B., cum laude, 1988)

Admissions

New Jersey

Pennsylvania

Supreme Court of New Jersey

Supreme Court of Pennsylvania

U.S. District Court for the Eastern District of Pennsylvania

U.S. Court of Appeals for the Second Circuit

U.S. Court of Appeals for the Third Circuit

U.S. Court of Appeals for the Fourth Circuit

U.S. Court of Appeals for the Ninth Circuit

U.S. Court of Appeals for the Tenth Circuit

U.S. Court of Appeals for the Eleventh Circuit