Stock index futures added to gains on Thursday after data showed weekly jobless claims dropped to their lowest level since May 2008, suggesting the labor market recovery was gaining speed, while a gauge of manufacturing in New York State showed growth accelerated in December.

S&P 500 futures rose 13.3 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 shot up 115 points, and Nasdaq 100 futures added 21.5 points. S&P futures are down more than 3 percent so far this week.

(Reporting by Edward Krudy; editing by Jeffrey Benkoe)