49 1/2 Floors Left

Larry Silverstein has made it official, after six months of rumors. This morning his company announced that about 50 Ameriprise Financial employees will occupy 20,000 square feet, half of the 39th floor, under a 10-year lease, starting this summer. Next fall, the only other outside tenant (Silverstein will take a floor also), the New York Academy of Sciences, will move in on the 40th floor. Given the time it takes a company to move out of its old place and outfit a new one, New Yorkers probably won't see that building fill up for many months after its official March opening, even if there is a rush on space.