US STOCKS-Futures edge lower after ADP misses forecasts

(Updates with futures' reaction ADP data)

NEW YORK, Aug 1 (Reuters) - U.S. stock index futures added to declines on Wednesday, indicating a weaker start for Wall Street, after a measure of private-sector employment was weaker than economists' forecast.

S&P 500 futures SPc1 were down 11 points, below fair value, a mathematical formula that evaluates pricing by taking into account interest rates, dividends and time to expiration on the contract.

Dow Jones industrial average futures DJc1 lost 85 points, and Nasdaq 100 NDc1 futures slid 12.75 points.