The housing market cooled in December, with fewer houses taking longer to sell and at lower prices.
Although average prices increased 1.4% on November's prices, the Real Estate Institute's more accurate Monthly Housing Price Index recorded a fall of 0.9%.
The index is adjusted so as to prevent changes in any single price bracket from dominating results.
Philip Borkin, an economist at Goldman Sachs JB Were, says the market is responding to recent rises in mortgage interest rates.
Despite December's monthly fall, the index rose 2.8% during the quarter, contributing to a 6.4% increase for 2009.
The less-accurate, unadjusted average showed a rise of almost 10% to $360,000, which was $5000 higher than in November a year earlier.
Real Estate Institute president Peter McDonald says the increase in the median price can be attributed to increased confidence in the market.
On a seasonally adjusted basis, houses took on average 36 days to sell, one day longer than in November, and the number of sales fell 3.5%.
