"Posternak represents a growing trend of firms that are attracted to the 24-hour-a-day amenity base of the Back Bay and Prudential Center," says David Provost, vice president at Boston Properties.

Among the tower's major tenants are Gillette Company, Digitas, MCI Telecommunications, NStar, Tower Technologies, Partners Health Care and Newsweek. Lease rates for this deal were not available but the average asking rent for similar space is about $38 per sf.

Prudential Tower, developed in 1965, is one of three first-class office buildings in the Prudential Center owned by Boston Properties. The others include the 25-story 101 Huntington Ave. and the 35-story 111 Huntington Ave. The Prudential Center, which is located in the Back Bay neighborhood, is comprised of 2.6 million sf of office space and 620,000 sf of retail space and is connected, via glass enclosed arcades, to the Hynes Convention Center and approximately 50% of the city's total hotel rooms.

While the city's vacancy rate continues to hover at about 16% according to Meredith & Grew's most recent statistics, the vacancy rate for tower space on floors 20 or above is only 6.4%, indicating that class A high-rise space is experiencing different dynamics than the market as a whole.