Stocks tumble on Ukraine tensions; Time Warner skids after

Credit: Reuters/Carlo Allegri

A trader works on the floor of the New York Stock Exchange in New York August 4, 2014.

China's services purchasing managers' index fell to 50.0 in July from a 15-month high of 53.1 in June, the lowest since November 2005 when the data collection began.

The data was partly offset by expansion in the euro zone's services sector at the second-fastest pace in three years. However, deflationary pressures continued to weigh on the region.

Two separate readings on the U.S. services sector are due in the first half hour after the market opens on Tuesday.

S&P 500 e-mini futures were down 5.5 points and fair value - a formula that evaluates pricing by taking into account interest rates, dividends and time to expiration on the contract - indicated a lower open. Dow Jones industrial average e-mini futures fell 35 points and Nasdaq 100 e-mini futures lost 9.5 points.

Gannett Co shares rose 6.3 percent in premarket trading after the publisher of USA Today said it would take full ownership of automotive website Cars.com and spin off its publishing assets into a publicly traded company as it focuses on its digital businesses.

Coach shares added 7.5 percent premarket after the high-end retailer reported better-than-expected quarterly revenue helped by a rise in sales in international markets.

Shares of solar and LED equipment maker GT Advanced Technologies rose 10.5 percent premarket a day after it raised the lower end of its full-year 2014 adjusted profit forecast, citing higher gross margins for the second half of the year.

Online coupon company RetailMeNot shares tumbled 22.1 percent premarket after it forecast quarterly revenue below analysts' average estimate.

(Reporting by Rodrigo Campos; Editing by Bernadette Baum)