The National Association of Realtors Thursday morning reported its Commercial Leading Indicator for Brokerage Activity fell 6.0% to an index of 109.2 in the fourth quarter from a downwardly revised reading of 116.1 in the third quarter. The indicator, based on a first-quarter 1990 index of 100, is 9.1% lower than it was in the fourth quarter of 2007.

The Realtors said the decline in commercial real estate activity, as measured by net absorption and the completion of new commercial buildings, is likely to weaken further over the next six to nine months.

A bright spot in the Realtor report was multifamily housing. The apartment rental market has held its own, with vacancy rates forecast to edge up only to 6.0% in third quarter of this year from 5.8% in the third quarter of 2008. Average rent is projected to grow 1.7% this year, following a 2.9% gain in 2008. The NAR also said multifamily net absorption should be 127,500 units in 59 tracked metro areas in 2009.

Explaining the stability in the apartment rental market, Robert Toothaker, chair of the NAR's Commercial Alliance Committee, said, "The apartment rental market is more stable simply because home sales are depressed."