U.S. stock index futures trimmed gains slightly on Thursday after new jobless claims rose more than expected last week, even as a drop in the four-week average indicated an improving labor market.

S&P 500 futures rose 2.5 points and were above 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 gained 34 points and Nasdaq 100 futures added 4.25 points.

(Reporting by Chuck Mikolajczak; editing by Jeffrey Benkoe)