Greenbrook Buildings, a private‑equity‑funded landlord that has spent the past several years snapping up properties across Manhattan and Brooklyn, is now facing a major legal challenge to the way it has handled rent‑stabilized apartments.
In the case Cox v. 36 S Oxford St, LLC, tenants from four Brooklyn buildings—36 South Oxford Street, 171 15th Street, 365 Fifth Avenue, and 70 Prospect Park West—allege that Greenbrook pushed units out of rent stabilization and raised rents without meeting the legal criteria for doing so. Their complaint centers on Individual Apartment Improvements, or IAIs, which allow landlords to increase rents only when they perform legitimate, value‑enhancing upgrades. The tenants say Greenbrook has never produced proof of the improvements it claims to have made, even as rents climbed sharply.
On June 11, 2026, Justice Lyle E. Frank of the New York County Supreme Court issued a Decision & Order granting class certification. The ruling allows tenants across the affected buildings to litigate their claims together and rejects Greenbrook’s arguments that each apartment’s rent history and alleged improvements should be evaluated individually. The Court’s decision clears the way for a unified examination of whether the landlord engaged in a broader pattern of improper deregulation.
Roger A. Sachar, a partner at Newman Ferrara and counsel for the tenants, remarked: “Class certification ensures that every tenant affected by this scheme will finally stand on equal footing, and Greenbrook will have to answer for what the evidence shows they did.”
With the class now certified, Greenbrook must either produce proof of the improvements it relied upon—or face the consequences of failing to do so.