The region's office market had a positive - albeit slightly - 2011, as the overall vacancy rate dropped from 19.2 percent to 18.6 percent, according to Newmark Knight Frank Smith Mack, a real-estate-services firm.

In all, about 661,000 square feet of real estate was filled in 2011, a substantial improvement over the emptying of 900,000 square feet in 2010.

However, the fourth quarter was a bit of a downer, with the region posting a net loss of 76,000 square feet of occupancy.

Newmark Knight said gains in Philadelphia's central business district did not make up for losses in the suburbs, northern Delaware and South Jersey.    - Diane Mastrull