Deal terms were not disclosed. However, comparable asking rents in the area range from $75 to $100 per square foot, and Studley's Greg Taubin says in a release that he and partner Craig Lemle "created the necessary leverage in the marketplace to bring the landlord to a fair market rental rate that enabled Mentor Partners to stay put at 500 Park."

Lemle says in the release that although the market was already softening when he and Taubin took the assignment in April 2008, "the landlord community hadn't conceded to the imminent downturn." Lemle and Taubin, senior managing directors at Studley, represented Mentor when the company moved across the street from 499 Park Ave. 15 years ago.

David Kleiner and Frank Doyle of Jones Lang LaSalle represented landlord Morgan Stanley in the transaction. Other tenants in the 202,340-square-foot 500 Park, located at the corner of East 59th Street, include Caxton Associates and Sandelman Partners LP.