Stock index futures added to gains on Wednesday after government data showed orders for U.S. durable goods rose by a much-stronger-than expected 1.8 percent in May.

S&P 500 futures rose 9.60 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 climbed 83 points, and Nasdaq 100 futures added 12.50 points.

(Reporting by Chuck Mikolajczak; editing by Jeffrey Benkoe)