Stock index futures extended losses on Thursday after data showed the domestic economy expanded as expected in the fourth quarter while initial jobless claims were slightly worse than expectations.

S&P 500 futures fell 5.5 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 26 points, and Nasdaq 100 futures shed 9 points.

(Reporting By Chuck Mikolajczak; editing by Jeffrey Benkoe)