U.S. stock index futures pointed to a lower open on Tuesday after U.S. home prices fell unexpectedly, adding to concerns about the strength of the economic recovery.

The S&P composite index of home prices in 20 metropolitan areas declined 0.2 percent in December, matching the dip in November, while a Reuters survey indicated prices would be unchanged for the month.

We still have a very high foreclosure rate and a high inventory held by banks, along with previously foreclosed houses and abandoned properties, Joseph Battipaglia, market strategist at Stifel Nicolaus in Yardley, Pennsylvania.

The focus on the economy overshadowed better-than-expected quarterly results from Home Depot Inc , as the top home improvement chain forecast a fiscal-year profit above estimates. Its shares were up more than 1 percent to $30.70 in premarket trade.

On a busy day for retail stocks, Target Corp reported higher quarterly profit as the No. 2 U.S. discount retailer avoided the drastic clearance sales that crimped results in its holiday quarter a year ago. But its shares slid 0.9 percent to $50.19 in premarket trade.

S&P 500 futures fell 4.1 points, Dow Jones industrial average futures were off 26 points, and Nasdaq 100 futures lost 6.75 points.

(Reporting by Edward Krudy; editing by Jeffrey Benkoe)