O’Melveny Worldwide

Abby Rudzin has more than two decades of experience defending financial institutions and Fortune 500 companies in high-stakes litigation matters, primarily in the securities and antitrust arenas. Her clients range from large financial institutions and investment banks to small private equity firms.

  • Represented Chinese company in successful U.S. Supreme Court case about class certification and statute of limitations tolling in securities fraud cases. This is the only known case in which a Chinese company has taken a securities fraud case to the U.S. Supreme Court.
  • Representing controlling shareholders of Chinese auto parts company in litigation arising out of their take-private transaction.
  • Obtained dismissal with prejudice for footwear company and its executives in a securities fraud class action arising from statements about the company’s growth prospects.
  • Lead counsel for Chinese on-line game operator in securities fraud class action challenging going-private transaction.
  • Obtained dismissal with prejudice for China’s leading on-line book sellers in securities fraud class action challenging going-private transaction.
  • Obtained dismissal with prejudice for footwear company and its executives in a securities fraud class action arising from statements about the company's expenses, primarily to grow China business.
  • Counsel for underwriters in securities fraud suit arising out of technology company’s initial public offering.
  • Defending private equity firm in securities fraud class action arising out of secondary offering to sell firm’s shares.
  • Lead counsel for investment bank accused of aiding and abetting special committee’s breach of fiduciary duty in approving related-party transaction.
  • Lead counsel for large derivatives exchange defending claims arising out of fraud perpetrated by futures commissions merchant engaged in trading on the exchange.
  • Lead counsel for large public insurance company defending litigation over shareholder books and records demand.
  • Defending financial services firm in numerous market manipulation and RICO claims filed around the country complaining about “naked short selling.”
  • Defending large financial institution in antitrust actions concerning credit card “swipe” fees.
  • Obtained dismissal of federal antitrust class action alleging that client and other leading private equity firms conspired to allocate the market for large leveraged buyout transactions by improperly forming “bidding clubs” for the acquisitions.
  • Obtained dismissal of federal securities class action for underwriting syndicate involved in initial public offering of Argentine energy company.


Bar Admissions

  • New York

Court Admissions

  • US Supreme Court
  • US Court of Appeals for the Second, Third, Fourth, Seventh, Eighth, and Ninth Circuits
  • US District Courts, District of Colorado, Northern District of Illinois, and the Eastern, Southern, and Western Districts of New York


  • The University of Chicago, J.D., 1995: with honors; Order of the Coif; Olin Foundation Fellowship in Law and Economics; Staff Member, The University of Chicago Law Review
  • Cornell University, A.B., Mathematics and Economics, 1991: cum laude; Phi Beta Kappa; Cornell Club of Maryland Scholarship
  • Oxford University, Oriel College, Oxford, England, 1989-1990

Honors & Awards

  • Named a Litigation Star in Securities (2023-2024) and Competition/Antitrust by Benchmark Litigation (2022-2024)
  • Recognized by Chambers USA for Securities Litigation (2023-2024)
  • Named to Crain’s New York Business “Notable Women in Law” (2019)
  • Litigator of the Week, The American Lawyer, January 4, 2018
  • US Supreme Court victory for China Agritech named a National Impact Case by Benchmark Litigation California, March 2019

Professional Activities


  • Honorable Frank H. Easterbrook, US Court of Appeals, Seventh Circuit (1996–1997)
  • Honorable Elaine P. Bucklo, US District Court, Northern District of Illinois (1995–1996)


  • "Defense Counsel: Let's Seal the Leaking American Pipe Doctrine", Wall Street Lawyer (July 2023)
  • “Winner’s Playbook: Behind the Scenes of China Ag v. Resh,” Law360 (August 22, 2018)
  • “From Chancery Court to Federal Court: The Obstacles to a Post-Trulia Migration,” The Review of Securities and Commodities Regulation (February 22, 2017)
  • “Protecting Financial Advisors in M&A Litigation,” The Review of Securities and Commodities Regulation (June 4, 2014)
  • “Loss Causation and Damages Defense Strategies,” Inside the Minds: Managing Securities Fraud Claims, Aspatore Books (2009)
  • “Loose Lips Sink Ships: The Importance of Director Confidentiality Programs,” Corporate Counsel Magazine (September 1, 2009)
  • “Future of Advancement and Indemnification Rights,” Securities Law360 (July 10, 2009)
  • “When Plaintiffs Overreach: Attacking Flawed Evidence of Loss Causation and Damages in Securities Class Actions (Parts One and Two),” Andrews Securities Litigation and Regulation Reporter (June 2, 2009, and June 16, 2009)


  • “Expert Witness Depositions,” Fundamentals of Taking and Defending Depositions, Practising Law Institute (February 2024)