SFProskauer Rose has taken two more floors at 11 Times Square — roughly 60,000 square feet that brings the law firm’s space in the Midtown tower to about 478,000 square feet. The expansion covers floors 31 and 32 and came with a 15-year renewal running in sync with the rest of the firm’s space and extending a lease that had been set to end in 2031.

Proskauer already held 14.5 floors up through the 30th. Its recent growth made the extra floors “very necessary for us,” said Hal Plott, the firm’s chief real estate and facilities officer.

The deal also secured options on further space beyond these two floors. Work on the 32nd floor is due to finish in early 2027.

The firm has been in the building since it opened. Proskauer moved from 1585 Broadway in January 2011, taking more than 400,000 square feet across floors 17 through 30 and putting its name on the top of the tower — the first New York law firm to do so at its own headquarters.

Expansion rights were part of the reason it chose the building in the first place: At the time, the firm said the appeal was 400,000 square feet of brand-new space plus room to grow into. Fifteen years later, it’s using that room.

Cushman & Wakefield’s Mark Weiss, Jon Herman and Mike Middleton acted for Proskauer, while CBRE’s Paul Amrich represented the landlord, SJP Properties. Rent terms were not disclosed.

The 1.1-million-square-foot tower at 640 Eighth Ave. on the corner of West 42nd Street (a block west of Times Square) was the last piece of the decades-long Times Square redevelopment. FXFOWLE Architects designed it, SJP built it with Prudential Real Estate Investors and it earned LEED Gold in part for an air intake 600 feet above the street.

Proskauer’s deal takes the building to a reported 93%  leased. Microsoft, consulting firm Synechron, and law firm Rabin Pfeffer and Partners also have space there.

Manhattan is both the tightest and the most expensive office market in the country. Vacancy in the borough was 10.2% in August, the lowest of the 25 largest U.S. markets and down 340 basis points over the year, against a national rate of 17.8%, according to Yardi Research data. Asking rents here averaged $72.70 per square foot, more than double the $33.20 national average. Class A space, the kind Proskauer occupies, is tighter still, at 9% vacancy compared with 12.2% for class B and 14.3% for class C.