Both the expiration of the homebuyer tax credit in the spring and the robo-signing scandal in the third quarter left their marks on the market in December, according to the Obama administration's most recent housing scorecard. New and existing home sales increased during the month, but still remained below levels seen in the first half of 2010. According to federal data, 27,400 new homes sold during December along with 440,000 existing homes. During the same period of 2009, almost 30,000 new homes and 453,000 existing homes sold. Foreclosure activity, including starts and completions, remained well below transaction levels seen in the first 10 months of the year. In November, the housing scorecard reported a 21% in foreclosure activity due to lenders recalling and reviewing foreclosure affidavits. Housing remained extremely affordable in December, as mortgage interest rates hovered near record lows. But the housing market "remains fragile," the scorecard said, because of unsettled home prices nationwide. The scorecard reported the rate for a 30-year fixed mortgage rate at 4.74%, down from 4.99% a year earlier. The median existing-home sale price in November was $168,000, according to the National Association of Realtors, down from $170,600 the prior month. Home prices were hurt by the number of discounted distressed home sales that took place. At last year's end, 4.7% of prime mortgage loans were delinquent as well as 36% of subprime mortgage loans and 12.8% of loans backed by the Federal Housing Administration, according to the scorecard. More than 4.1 million modification arrangements were started between April 2009 and the end of November 2010 — more than double the number of foreclosure completions during that time. These included more than 1.4 million trial Home Affordable Modification Program starts, more than 650,000 Federal Housing Administration loss-mitigation and early-delinquency interventions, and more than 2 million proprietary modifications under Hope Now. The Department of Housing and Urban Development and the Treasury Department compiled data for the monthly scorecard. HUD Assistant Secretary Raphael Bostic commended the administration on its efforts to offer alternatives to foreclosure, but acknowledged that there is still more work to be done. "We know that many responsible homeowners are still fighting to make ends meet," Bostic said. "Over the last 20 months, the Obama Administration has confronted the nation’s housing crisis with an unprecedented effort to promote stability in the market — keeping millions of families in their homes and helping millions more to save money by refinancing. But the data clearly show that the market remains extremely fragile." Write to Christine Ricciardi. Follow her on Twitter @HWnewbieCR.