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* Facebook surges after upbeat 4th-qtr, boosts Nasdaq futures
* Microsoft dips as Azure revenue growth slows
* Details awaited on U.S.-China trade talks
* Futures: Dow off 0.36 pct, S&P down 0.10 pct, Nasdaq up 0.22 pct (Adds comment, details, updates price)
By Sruthi Shankar
Jan 31 (Reuters) - The S&P 500 was set to open flat on Thursday following the Federal Reserve's pledge to be patient on further interest rate hikes and stellar results from Facebook Inc, as anxious investors awaited the outcome of the U.S.-China trade talks.
The benchmark index closed at the highest level since Dec. 12 on Wednesday after the U.S. central bank said it would be patient in raising rates further this year, pointing to a cloudy outlook for the U.S. economy.
The Fed's reassurance on rates along with heartening results from tech companies including Apple Inc and Facebook set the main U.S. indexes on track for their best month in about three years.
"Right now we have positive earnings, positive economy and a positive Fed, but the only missing piece of the puzzle is trade," said Andre Bakhos, managing director at New Vines Capital LLC in Bernardsville, New Jersey.
"It seems as if most of the fears have been taken away except for trade, which is holding back markets. It's still a wait-and-see approach."
U.S. President Donald Trump expressed optimism about high-level trade talks with Chinese officials in Washington but said no final deal would be made until he meets with Chinese President Xi Jinping in the near future.
The two countries opened a pivotal round of talks on Wednesday aimed at bridging deep differences over China's intellectual property and technology transfer practices and easing a months-long tariff war.
Facebook jumped 10.8 percent in premarket trading, boosting the Nasdaq futures after its quarterly profit topped analysts' estimates, showing that digital advertisers were still flocking to spend money on the service even after a series of high profile embarrassments.
General Electric Co jumped 11.3 percent after the industrial conglomerate beat estimates for sales and cash flow in the fourth quarter.
Fourth-quarter earnings reports have largely exceeded market expectations so far, helping U.S. stocks recover from a December selloff that was fueled by concerns about trade disputes, rising interest rates and fears of diminishing corporate profits.
After the latest Fed announcement, market expectations of future rates fell further. Contracts tied to the Fed's policy rate continued to price in a one-in-four chance of a hike in 2019.
At 8:49 a.m. ET, Dow e-minis were down 91 points, or 0.36 percent. S&P 500 e-minis were down 2.75 points, or 0.10 percent and Nasdaq 100 e-minis were up 14.75 points, or 0.22 percent.
Set to weigh on the Dow was Microsoft Corp, which fell 2.8 percent as its Azure cloud computing sales grew at a slower pace than a year earlier, although quarterly results and forecast topped Wall Street estimates.
DowDuPont Inc fell 8 percent after the chemicals maker's revenue fell short of expectations.
Tesla Inc dropped 3.4 percent after the electric carmaker missed Wall Street profit targets for the end of 2018 and announced the departure of its chief financial officer.
Chipmaker Qualcomm Inc rose 2.4 percent after posting quarterly earnings that beat Wall Street targets. (Reporting by Sruthi Shankar and Shreyashi Sanyal in Bengaluru; Editing by Shounak Dasgupta)