U.S. stock index futures extended losses on Friday after the U.S. dollar strengthened and homebuilder D.H. Horton Inc (DHI.N) reported a quarterly loss.

* S&P 500 futures SPc1 fell 9.4 points and were below fair value, a formula that evaluates pricing by taking into account interest rates, dividends and time to expiration on the contract. Dow Jones industrial average futures DJc1 dropped 80 points, and Nasdaq 100 futures NDc1 slid 10.25 points.