Leases  ·  Office

Hart Howerton Renews 27K-SF Office Lease at 10 East 40th Street


Architecture firm Hart Howerton has renewed its 27,111-square-foot lease for an additional 13 years and 6 months at Madison International Realty’s 10 East 40th Street, according to the landlord.

Madison International Realty, which is renovating the common areas of the building on 40th Street between Fifth and Madison avenues, did not disclose the asking rent. But in Midtown, asking rents averaged $76.95 per square foot in the first quarter of 2023, according to a Cushman & Wakefield report.

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Hart Howerton occupies the 37th through 39th floors of the building, which was constructed in 1929. Long known as the Mercantile Building, it is being rebranded as Tower 40.

“In this challenging office environment, the new tenants at Tower 40 constitute a positive indicator that demonstrates the continuing appeal of quality buildings in Midtown,” Diana Shieh, managing director at Madison International Realty, said in a statement. “We believe the rebrand conveys the extent to which this historic building is being modernized with the infrastructure and services that tenants demand.” 

Madison International and its partner in the building, Joseph P. Day Realty, were represented by Ethan Silverstein, Theodora Livadiotis and Caroline Collins of C&W while Ryan Alexander and Tim Freydberg of CBRE (CBRE) negotiated on behalf of Hart Howerton. C&W and CBRE did not immediately respond to requests for comment.

Other recent leases in the building include investment firm Alpha Square Group, which leased 8,769 square feet on the 35th floor, and Italian fashion house Missoni, which took 3,800 square feet of penthouse space on the 48th floor.

Alpha Square Group was represented by Evan Algier and Steven Langton of C&W, and Diego Rodino di Miglione — also from C&W — brokered the deal on behalf of Missoni.

Mark Hallum can be reached at