U.S. stock index futures briefly extended losses before reversing in choppy trade on Thursday after data on initial jobless claims, producer prices and retail sales.

S&P 500 futures fell 4.4 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 57 points and Nasdaq 100 futures dropped 13 points.

(Reporting by Chuck Mikolajczak)