Existing U.S. home sales slipped 1.7 percent in September compared with August, but home listings remain tight, a trade group in Washington said Friday. Existing home sales in September fell to 4.75 million on a seasonally adjusted annual basis, down from 4.82 million in August, the National Association of Realtors said. NAR said the median sales price for existing homes rose on an annual basis for the seventh consecutive month -- the longest streak since November 2005 to May 2006. The median price of $183,900 is 11.3 percent higher than September 2011, the trade group said. The total inventory of homes on the market fell 3.3 percent from August to 2.32 million existing homes listed, a 5.9-month supply at the current rate of sales. The supply line is down from a 6-month supply at the end of August. The inventory of homes for sale is also 20 percent lower than September 2011, when there was an 8.1-month supply. \"The shrinkage in housing supply is supporting ongoing price growth, a pattern that could accelerate unless home builders robustly ramp up production,\" said NAR Chief Economist Lawrence Yun.