Stock index futures extended losses on Friday after reports that Standard & Poor's could downgrade the credit rating of several euro zone members as early as Friday.

S&P 500 futures fell 11.9 points and were below fair value, a formula that evaluates pricing by taking into account interest rates, dividends and time to expiration of the contract. Dow Jones industrial average futures lost 80 points, and Nasdaq 100 futures dropped 12.5 points.

(Reporting by Rodrigo Campos; editing by Jeffrey Benkoe)