* Alphabet, Amazon tumble on weak results, forecasts
* Growth stocks hit; Facebook, Apple, Netflix down 2-5 pct
* GDP data at 8:30 a.m. ET to show growth slowed in Q3
* Futures sink: Dow 0.96 pct, S&P 1.23 pct, Nasdaq 2.38 pct
* S&P and Dow set to move back into the red for the year
Oct 26 (Reuters) - U.S. stock index futures plunged on Friday as disappointing results from behemoths Amazon and Alphabet rekindled a rush to dump technology and high-growth stocks, ahead of data that will likely show U.S. economic growth slowed last quarter.
The Nasdaq Composite was set to cut its gains for the year in half as Nasdaq 100 e-minis sank over 2 percent. S&P 500 e-minis and Dow e-minis shed about 1 percent each, which would be enough to push both the indexes back into losses for the year.
Amazon.com Inc tumbled 9.5 percent in premarket trading after it not only missed quarterly sales estimates, but also gave a below par holiday-season sales forecast. Its cloud unit, Amazon Web Services, only narrowly beat estimates.
Google-parent Alphabet Inc sank 6.1 percent after its revenue missed estimates, fanning concerns that investments in new businesses, rising regulatory scrutiny and competition are producing slow, unpredictable returns.
The reports triggered a pullback in other members of the so-called FAANG group. Facebook Inc fell 3.3 percent, Apple Inc slid 2 percent and Netflix Inc dropped 4.7 percent.
A clutch of weak outlooks on Wednesday had led the Nasdaq to confirm a correction and erased the Dow and the S&P 500's gains for the year. On Thursday, Microsoft Corp's strong earnings led a rally that pulled the S&P and Dow back into the black for 2018.
"Risk aversion is alive and kicking on Friday, as weaker than expected tech earnings trigger the latest stampede and those still buying the dips once again get burned," Craig Erlam, senior market analyst at online forex broker Oanda, said in a note.
"Earnings season has more to run, so there's plenty of time for companies to turn this funk around. But, as yet, they haven't given investors the boost they well and truly need."
While investors grapple with a slowdown in the bumper corporate profit growth, they are now also faced with a scenario of U.S. economic growth also taking a breather after months of strength.
U.S. GDP growth likely slowed to a 3.3 percent annualized rate in the third quarter, from 4.2 percent in the prior quarter, data at 8:30 a.m. ET (1230 GMT) is expected to show.
"Today's number could give signs if we are close to peak earnings for U.S. corporates. Housing data and consumer goods durables data has been soft lately," said Sim Moh Siong, currency strategist at Bank of Singapore.
At 6:56 a.m. ET, Dow e-minis were down 239 points, or 0.96 percent. S&P 500 e-minis were down 33 points, or 1.23 percent, and Nasdaq 100 e-minis were down 164.75 points, or 2.38 percent.
Microsoft, whose strong results helped push the Nasdaq to its biggest daily gain since March just a day earlier, fell 4.7 percent.
Intel Corp was up only 0.4 percent as its better-than-expected quarterly results were clouded by interim Chief Executive Bob Swan saying trade tensions with China could be a "headwind" next year.
The pullback in U.S. corporate and economic growth has heightened investors worries that a decade-old bull market may be ending and triggered a whipsaw in the market for the past few weeks. Despite Thursday's pop, the S&P is down 7.2 percent this month, on pace for its worst month in seven years. (Reporting by Amy Caren Daniel in Bengaluru; Additional reporting by Tom Finn; Editing by Arun Koyyur)