Jayme Jonat

Jayme Jonat represents entities in high-stakes commercial litigations, often touching on securities- and antitrust-related issues. Equally comfortable representing plaintiffs and defendants, she has been involved in numerous large-scale litigation efforts that, in addition to their considerable monetary stakes, have tested new legal theories and affected business practices across entire industries.

She plays a prominent role in the defense of Visa in antitrust actions brought by some of the largest retailers in the world over “swipe fees.” Jayme helped Visa reach a historic $6.26 billion settlement with one class of merchants, the largest known settlement of a private antitrust case under the 120-year-old Sherman Act. In March 2023, the U.S. Court of Appeals for the Second Circuit approved the final settlement. In November 2025, Visa, along with Mastercard, announced a more than $200 billion settlement with over 12 million merchants. In June 2026, U.S. District Judge Brian M. Cogan granted preliminary approval of the settlement, bringing final resolution of two decades of antitrust litigation over swipe fees one step closer.

Jayme also spearheaded two first-of-their-kind discrimination lawsuits against Frontier Airlines, alleging that its policies toward pregnant and breastfeeding pilots and flight attendants violated the Civil Rights Act. In 2022, Frontier settled the lawsuit on behalf of flight attendants, agreeing to allow flight attendants to use breast pumps in flight and to identify lactation facilities at its base airport locations. In December 2023, Frontier settled the pilots’ lawsuit, marking a critical step toward gender equity in the airline industry and helping redefine what parental accommodations should look like in the workplace.

In January 2024, Jayme helped the online video platform Rumble Inc. win dismissals of two putative class actions alleging Rumble violated the Video Privacy Protection Act by disclosing subscriber information to Facebook.

Jayme also led the HSG team representing AmTrust North America, Inc. in a breach-of-contract and breach-of-fiduciary-duty action in New York Supreme Court against its managing general agent arising out of an insurance program that allegedly caused losses exceeding $200 million. The dispute settled favorably for HSG’s client.

Jayme assisted Judge Holwell in his role as an independent monitor appointed by a major financial institution under an agreement with the SEC. She also represented Sealed Air in a securities fraud class action in the Southern District of New York. In January 2023, the court approved a $12.5 million settlement.

Beyond her client work, Jayme was the first woman to serve as administrative partner of HSG, helping lead operations, recruiting, and professional development. She has been named to the Lawdragon 500 X – The Next Generation since 2023 and has been recognized as a Notable Woman in Law by Crain’s New York Business, a Litigation Trailblazer by The National Law Journal, a Benchmark Litigation 40 & Under honoree, a Rising Star by Euromoney, and a Woman Worth Watching by Profiles in Diversity Journal.

Prior to joining HSG, she was a litigation associate at Davis Polk & Wardwell LLP and clerked for the Honorable Arthur D. Spatt of the U.S. District Court for the Eastern District of New York.