Lawyer Barry Fox of New York could be in danger of losing his penthouse apartment after an appellate court ruled he isn’t entitled to rent-stabilization protections.

Fox, senior counsel with Cleary Gottlieb Steen & Hamilton, who lived in the Upper East Side building since 1975, never knew his former landlord was getting tax benefits for his apartment being rent-stabilized. He was paying market rent—$25,000 per month—and it wasn’t until 2014, when his building changed hands and a new landlord said it wasn’t going to renew his lease, that he learned he might have protections against eviction.