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.
Jayme is a core member of the HSG team defending Visa in a sprawling multidistrict antitrust litigation over “swipe fees” brought by major retailers. Jayme helped achieve a $6.26 billion settlement—the largest private antitrust settlement in U.S. history—approved by the Second Circuit in 2023. In the opt-out proceedings still underway, she is preparing for trial scheduled for April 2026 against corporate giants including Target, Macy’s, and many others.
Jayme 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
Among other recent notable matters, Jayme has represented Sealed Air—the maker of bubble wrap—in a securities fraud class action in the SDNY that ultimately settled for $12.5 million, and the online video platform Rumble Inc. in obtaining dismissals of two putative class actions alleging Rumble violated the Video Privacy Protection Act by disclosing to Facebook the personal information of subscribers. Jayme has also assisted Judge Holwell in his role as an independent monitor appointed by a major financial institution under an agreement between the institution and the SEC.
Currently, Jayme is a key member of the HSG team representing an insurance company in an ongoing breach-of-contract action in New York Supreme Court against its managing general agent arising out of an insurance program allegedly misoperated by the agent, causing losses of over $200 million.
Jayme maintains a diverse pro bono practice, providing legal assistance to underserved communities across the country. For example, in partnership with the ACLU of Louisiana’s Justice Lab, Jayme filed a high-stakes pro bono lawsuit against police officers for using excessive force against a cooperating Black man with pre-existing injuries in which she secured a favorable settlement in the federal civil rights case.
Beyond her client work, Jayme was the first woman to serve as administrative partner of HSG, a position of immense responsibility, where she helped lead operations, recruiting, and professional development. She exemplifies influence in the broadest and most meaningful sense: she shapes law, uplifts colleagues, mentors the next generation, and drives institutional change. In a profession where gender equity remains elusive at the top, Jayme has broken through—and opened doors for those coming after her. She has been named to the Lawdragon 500 X – The Next Generation since 2023, and has been recognized as a Notable Woman in Law (Crain’s New York Business), Litigation Trailblazer (The National Law Journal), 40 & Under Hot List member (Benchmark Litigation), Rising Star – Best in Litigation shortlist honoree (Euromoney), and a Woman Worth Watching (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.
