Wall Street braces for weak open on tech earnings

U.S. stock markets were expected to open lower on Wednesday in the wake of disappointing earnings from tech heavyweights.

More earnings are on the calendar this session, with Boeing, Coca-Cola, American Express, Qualcomm and Texas Instruments among those companies reporting.

Existing home sales data for June are due out at 10 a.m. ET, although economic data may play second fiddle to earnings season for now.

Apple's shares tumbled almost 7 percent in after-hours trade on Tuesday after the firm's fourth-quarter revenue forecast fell short of forecasts and it missed some targets for iPhone sales.

Read MoreApple's real earnings problem: The forecast

Microsoft shares, meanwhile, fell more than 3 percent in late trading after posting a $3.2 billion net loss for its fiscal fourth quarter ending June 30 following restructuring charges.

The slide in tech stocks set the tone for trade in global equity markets: Asian stocks closed mostly lower, while Europe's main bourses were all in the red in early trade.

U.S. stock futures traded broadly lower, with benchmark Dow Jones industrial average futures trading about 70 points lower after trimming earlier losses.

The New York Stock Exchange
Getty Images
The New York Stock Exchange

"I think the analysts are wrong on this, Apple (earnings report) was broadly in line with what the market was expecting and we see this as a buying opportunity," Cyrus Mewawalla, managing director at CM Research told CNBC's "Worldwide Exchange" on Wednesday.

Read MoreBruised tech could be drag for stocks

U.S. stocks closed lower on Tuesday, with lackluster earnings sending the Dow Jones down 1 percent, while the tech-heavy Nasdaq retreated from the week's record peaks.

"Despite record highs in the Nasdaq over the past few days, the move higher has been increasingly divergent from the Russell 2000 and Dow both of which are still significantly below their May highs, while the S&P 500 only just about managed to get within a whisker of its previous peaks, so the decline that we saw yesterday shouldn't really have been a surprise," Michael Hewson, chief Market Analyst at CMC Markets UK, said in a note.

"These divergences suggest U.S. markets look overstretched, and the strength of the U.S. dollar could well be a factor in this," he added.

Read MoreEarly movers: BA, KO, XOM, CPB, WHR, EMC, Z & more

Elsewhere, Greece was back in the spotlight with the country's parliament due to vote on Wednesday on a second set of reforms that lenders have demanded in exchange for further bailout funds.

Greek Prime Minister Alexis Tsipras faces a growing revolt within his anti-austerity Syriza party over the legislation.