U.S. stock index futures extended losses on Thursday after weekly jobless claims rose slightly more than expected in the latest week.

S&P 500 futures fell 27.3 points and were sharply 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 228 points, and Nasdaq 100 futures dropped 47.75 points.

(Reporting by Angela Moon; editing by Jeffrey Benkoe)