Average home prices improved for the second consecutive quarter nationwide in the third quarter this year, according to a S&P/Case-Shiller Home Price Indices report released today, while the New York City housing market stayed fairly stable month-over-month (see the full report below). The U.S. National Composite data in the S&P report jumped 3.1 percent from the previous quarter. Still, while quarter-over-quarter data is up, year-over-year data remains on the decline. The index recorded an 8.9 percent decline in third-quarter 2009 data over figures recorded during the same time period a year earlier. A bright point in the report is the monthly data recorded on the 10- and 20-city composite scale. Both those scales posted their fifth consecutive monthly increase as of September this year. Still, David Blitzer, chairman of the Standard & Poor’s Index Committee, cautioned against too much optimism. “We have seen broad improvement in home prices for most of the past six months,” Blitzer said. “However, the gains in the most recent month are more modest than during the seasonally strong summer months.” The New York metropolitan figures stayed somewhat steady month-over-month, according to the report, with its September index score of 174.38 showing a .3 percent decline over August.