Stock futures extended losses on Thursday as further labor market weakness fueled doubts about a quick economic recovery and Britain's reduced rating outlook signaled more fallout from the credit crisis.

S&P 500 futures fell 10 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 shed 90 points, and Nasdaq 100 futures dipped 15 points.

(Reporting by Ellis Mnyandu; additional reporting by Ryan Vlastelica; editing by Jeffrey Benkoe)