Nathan Berman

The Manhattan-based company that Nathan Berman founded has some 4,000 housing units under development spanning 3 million square feet.

The figures are impressive, but pale against some of the other names on this list. That is, until it becomes clear the nature of the development. Berman and company are the nation’s most prominent converters of commercial office space into residences. And they’re doing it at a time when such conversions are very much in vogue.

That’s because the pandemic accelerated the obsolescence of non-Class A space. It’s also because the alternative — ground-up construction — is a tougher road in major urban markets such as New York. As Berman told Commercial Observer in spring 2025, office-to-residential projects are “the only viable path today to delivering market-rate units, because with construction costs, land costs and the interest rate environment, ground-up construction without any tax abatements doesn’t pencil.” 

As of 2025, Berman’s company and its partners had various conversions in the works. Those included New York City’s largest such project ever, the conversion of the old Pfizer headquarters into a 1.3 million-square-foot, 1,600-unit complex. There’s also 767 Third Avenue (282,000 square feet into 337 apartments) as well as 675 Third Avenue (343,000 square feet into 464 units) and 111 Wall Street (1.3 million square feet into 1,580 apartments).

Near that last ongoing conversion is the completed 25 Water Street. Often described as the largest U.S. office-to-residential conversion to date (or until that Pfizer HQ redo is done), it turned 1.3 million square feet into 1,320 apartments. And, also in Manhattan’s Financial District, there’s 55 Broad Street, where MetroLoft and Silverstein Properties converted 410,000 square feet into 571 apartments. Both wrapped in 2025.

The partners put 55 Broad up for sale in September with an asking price of $500 million-plus, thus hoping to convert the conversion into something truly lucrative.