Stock index futures pointed to a lower open on Wall Street on Friday, with equities poised to reverse recent strong gains after Google's results, and ahead of General Electric and Bank of America earnings.

At 4 a.m. EDT, futures for the S&P 500 were down 0.36 percent, Dow Jones futures were down 0.27 percent and Nasdaq 100 futures were down 0.32 percent.

Google posted a 23 percent jump in quarterly revenue on a rebound in Web advertising, but its stock fell 5 percent as the company disappointed some investors accustomed to blowout results. Google shares traded in Frankfurt were down 4.2 percent.

Advanced Micro Devices Inc reported better-than-expected first-quarter revenue as PC and server spending rebounded, but investors cashed out of a rally triggered by stellar Intel Corp results. Shares of AMD traded in Frankfurt were down 4.1 percent.

Continental Airlines Inc has restarted merger talks with UAL Corp's United Airlines, two years after walking away from almost sealing a deal, a source briefed on the matter said on Thursday.

Companies scheduled to report quarterly results on Friday include General Electric , Bank of America , Mattel and First Horizon National . Economic indicators on tap for Friday include March housing starts and University of Michigan sentiment data for April.

Tech shares will also be in focus after mobile phone maker Sony Ericsson <6758.T> swung to a surprise first-quarter pretax profit on Friday as its push into the growing smartphone market and hefty cost cuts boosted margins.

U.S. crude dropped to below $85 on Friday as concerns about U.S. demand re-emerged and the dollar strengthened, making imports more expensive for emerging economies where consumption is surging.

Japan's Nikkei average lost 1.5 percent on Friday, putting in its lowest close in nearly three weeks, while European shares were down 0.2 percent in morning trade, with shares in airlines and airport operators under pressure as a huge ash cloud from an Icelandic volcano caused air travel chaos across Europe and beyond, leaving hundreds of thousands of passengers stranded.

U.S. stocks posted their sixth straight day of gains on Thursday as an encouraging profit forecast from United Parcel Service lifted transportation shares, though concerns about a rise in weekly jobless claims limited the market's advance.

The Dow Jones industrial average <.DJI> rose 21.46 points, or 0.19 percent, to end at 11,144.57. The Standard & Poor's 500 Index <.SPX> edged up 1.02 points, or 0.08 percent, to 1,211.67. The Nasdaq Composite Index <.IXIC> gained 10.83 points, or 0.43 percent, to close at 2,515.69.

(Reporting by Blaise Robinson; editing by Simon Jessop)