S&P 500 and Nasdaq futures turned negative, while Dow futures pared gains on Tuesday, as investors turned anxious about the potential strength of an economic recovery ahead of earnings season.

* S&P 500 futures fell 2.40 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 were up 8 points, but Nasdaq 100 futures slipped 2.50 points.

(Reporting by Leah Schnurr; Editing by Padraic Cassidy)