SL Green Sells 49% Stake in 346 Madison Avenue to Mori Building Co.
The two companies will form a joint venture to build a new office tower on the site
By Isabelle Durso May 27, 2026 6:08 pm
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SL Green Realty has sold a 49 percent stake in 346 Madison Avenue to Japanese developer Mori Building Company at a gross valuation for the office tower of $175 million, SL Green announced Wednesday.
The two companies will form a joint venture to develop a new 46-story, 850,000-square-foot office tower at the Midtown site one block away from Grand Central Terminal. KPF will design the tower.
As part of the deal, SL Green, New York City’s largest office landlord, will keep a 51 percent stake in the project and serve as the development and leasing manager, according to the firm.
“346 Madison Avenue will set a new benchmark for innovative office development in East Midtown, and Mori Building is the ideal partner to join us in the realization of that vision,” Marc Holliday, chairman and CEO of SL Green, said in a statement. “Tenant demand for the highest-quality, best-located and most thoughtfully designed buildings far exceeds available supply. This is the perfect moment for SL Green and Mori Building to conceive and build the next great New York City office building.”
Once complete, the new office tower across the street from SL Green’s One Vanderbilt is expected to feature a two-floor amenity center including a 215-seat auditorium, a tenant lounge, an outdoor terrace and a fitness center. A “world-class restaurant” will occupy ground-floor retail space, according to SL Green.
“We are pleased to advance Mori Building’s first development project in New York alongside SL Green,” said Shingo Tsuji, president and CEO of Mori. “By uniting the expertise and networks of both SL Green, a driving force in shaping Manhattan’s urban landscape, and Mori Building with its deep experience in large-scale urban development in Tokyo, we will create a new landmark that defines New York City.”
SL Green bought 346 Madison Avenue from Claudio del Vecchio, the former owner of Brooks Brothers, for $160 million in September 2025.
Isabelle Durso can be reached at idurso@commercialobserver.com.
