Stock futures turned negative, erasing early gains on Thursday as European equities fell to a session low.

S&P 500 futures were off 15 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 lost 129 points and Nasdaq 100 futures sank 17.5 points.

European shares were pressured as French banks fell, extending the previous day's losses on concerns about the sector's outlook.

(Reporting by Ryan Vlastelica)