* Ford, Lincoln, Mercury sales fall 6 pct in September
* Q3 sales up 5 percent, Ford gains market share
* Ford shares down 2.2 percent (Adds background on third-quarter sales, profitability forecast, updates stock price)
DETROIT, Oct 1 (Reuters) - Ford Motor Co F.N said on Thursday its U.S. auto sales fell 5 percent in September from a year earlier as demand slumped off in part due to the end of the U.S. government's "cash for clunkers" incentive program.
For the third quarter, Ford said sales for its core Ford, Lincoln and Mercury brands were up 5 percent, the only quarterly sales gain for a major automaker in the U.S. market.
Ford, the only U.S. automaker to have avoided bankruptcy, is targeting a return to profit by 2011 and has been gaining market share at a time when industry-wide sales remain weak.
The company has said it expects industry-wide sales in September to be near 9 million to 9.5 million units on the annualized and adjusted basis tracked by analysts, near the low point for sales that the U.S. market hit in February.
For September, sales at Ford's core brands Ford, Lincoln and Mercury fell 6 percent compared with a year earlier.
Including Volvo, Ford's U.S. sales fell to 114,655 vehicles in September, from 120,788 vehicles a year earlier, a decline of just over 5 percent.
Auto sales across the industry dropped sharply in September compared with August, when the government's sales incentive program pushed the industry to its best sales results of 2009.
Ford said retail sales through showrooms were down 14 percent in September from a year earlier while sales to fleet customers, including car rental agencies, were up 23 percent.
The government's clunkers incentive program boosted U.S. sales from the last week of July through the first three weeks of August.
In September, industry analysts and executives said sales were on track for a sharp pullback due to weaker demand, low inventories at dealerships and reduced incentive spending by automakers.
Ford expects a gradual recovery in U.S. auto industry sales as the economy recovers and consumer confidence returns.
Ford expects U.S. auto industry sales for 2009 to come in at about 10.5 million vehicles to 11 million vehicles including medium and heavy duty trucks. It expects 2010 U.S. auto industry sales of about 12.5 million vehicles.
Sales at Ford's Volvo brand rose 16 percent to 4,716 vehicles in September. Ford has said it is in talks with interested parties to sell the Volvo brand.
Ford shares were down 16 cents or 2.2 percent at $7.05 on the New York Stock Exchange in early afternoon on Thursday. (Reporting by David Bailey, editing by Matthew Lewis)