Stock index futures extended losses on Friday after data showed U.S. employment growth ground to a halt in August, underscoring fears about a weakening economy.

S&P 500 futures lost 20.20 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 fell 155 points, and Nasdaq 100 futures dropped 32.25 points.