[This quarterly market report is provided by Dr. Kevin Gillen, an economist at the Real Estate Department of the Wharton School and Fellow of the University of Pennsylvania. He analyzes the Philadelphia real estate market using the city’s real estate database through Hallwatch , a watchdog group. The results are published in a research paper called Philadelphia House Price Indices each quarter as a public service to the Philadelphia real estate community. Here’s his methodology [pdf]. 
Its informative and I am glad I am able to present his efforts on Matrix] -Jonathan Miller
The Philadelphia real estate market nominal price gains as inventory continued to climb.
Average appreciation from the prior quarter was 0.6% while appreciation from the prior year quarter was 11.4%
Citywide, total sales volume stood at 6,723 (arms-length) transactions, the slowest 3rd quarter in 3 years
More discussion concerning the report [Hallwatch.org].  Hallwatch  is a private and independently maintained watchdog website that does a lot of in-depth, independent and investigative pieces on city politics, as well as real estate.