S&P index futures added to their losses on Thursday after data showed an unexpected rise in weekly jobless claims.

Separately, U.S. core producer prices rose slightly faster than expected in March.

Futures had been lower over concerns about Chinese inflation.

S&P 500 futures fell 7.4 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 36 points and Nasdaq 100 futures lost 14 points.

(Reporting by Ryan Vlastelica; Editing by Kenneth Barry)