Marni has extensive experience representing clients in federal and state court litigation, in both civil and criminal matters. She routinely represents clients before arbitration panels at FINRA and the American Arbitration Association and represents the financial services industry and individual securities professionals during investigations and enforcement proceedings before state and federal regulators and other regulatory authorities. Marni has handled matters involving a wide range of issues including securities/commodities fraud, sales practice violations, improperly unregistered offerings, stock manipulation, insider trading, mutual fund trading practices, front running, violations of other federal statutes and SRO rules, breach of contract and corporate raiding.

Marni began her career as a trial attorney for the New York City Legal Aid Society - Criminal Defense Division where she handled over 2,500 cases from inception to final disposition, including numerous jury and bench trials to verdict. Subsequently, Marni represented clients charged with federal and state criminal offenses, including securities and other business frauds, for a well-respected trial and appellate attorney in Manhattan. She then transitioned her career to specializing in securities industry litigations while employed with a Wall Street securities boutique law firm. Prior to joining McCormick & O'Brien, Marni was of Counsel to Herrick, Feinstein LLP, a full service, business law firm headquartered on Park Avenue in Manhattan.

Marni earned her J.D. at Tulane Law School (1993) and her B.A. at the State University of New York at Binghamton (n/k/a Binghamton University) (1990). She is admitted to practice law before the courts of the State of New York and the Southern and Eastern Districts of New York.