Futures add to gains after home price data

U.S. stock futures added to gains on Tuesday after data showed U.S. home prices rose more than expected in May.

S&P 500 futures rose 6.9 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.

(Reporting by Caroline Valetkevitch; editing by Jeffrey Benkoe)