* Amazon shares fall after results; Visa, Ford also down
* Microsoft edges higher as earnings beat expectations
* Investors concerned about fallout from Ukraine violence
* Dow off 0.9 pct; S&P 500 down 0.8 pct; Nasdaq off 1.8 pct
(Updates to close)
NEW YORK, April 25 (Reuters) - U.S. stocks fell on Friday, pulled lower by a selloff in consumer discretionary stocks as bellwether names Amazon.com and Ford Motor fell in the wake of their quarterly earnings.
Amazon was the S&P 500's worst performer, down 9.9 percent to $303.83, and other high-flying sectors dropped along with it. Social media names slid, with Twitter losing 7.1 percent to $41.61, and the Nasdaq Biotechnology Index falling 2.4 percent as investors once again shied away from riskier sectors. The Global X Social Media index ETF tumbled 5.3 percent, its second-worst performance since its debut in November 2011.
Still, even with Friday's decline, the S&P 500 finished nearly flat for the week. The benchmark index remained within 2 percent of its all-time intraday high.
Amazon's stock declined a day after the company reported a jump in quarterly revenue, which was offset by sharp increases in spending.
Ford Motor Co shares fell 3.3 percent to $15.78 after the No. 2 U.S. automaker reported first-quarter earnings that missed expectations. The company's results were hurt by higher warranty costs in North America.
The two weighed on the S&P index of consumer discretionary stocks, which dropped 1.7 percent and ranked as the worst-performing sector of the day.
"What that says is people are using any strength at all to raise some cash because they think the market is going to test lower," said Ken Polcari, director of the NYSE floor division at O'Neil Securities in New York.
Investors continued to pay attention to geopolitical strife over Ukraine, creating some nervousness heading into the weekend. U.S. President Barack Obama and four European allies agreed on Friday that Russia failed to live up to terms of the Ukraine peace accord, and would coordinate on a response to "impose costs" on Russia, the White House said.
While the situation has taken a backseat to corporate earnings recently, investors remain on edge over the possible result of escalating tensions. Visa Inc said late Thursday that U.S. sanctions on Russia were hurting its card transaction volumes. Visa's stock dropped 5 percent to $198.93 and weighed on the Dow.
On the upside, Microsoft Corp's earnings topped analysts' forecasts, while investors were cheered by the software company's new emphasis on mobile and cloud computing. Microsoft's stock edged up 0.1 percent to close at $39.91.
The Dow Jones industrial average fell 140.19 points or 0.85 percent, to end at 16,361.46. The S&P 500 dropped 15.21 points or 0.81 percent, to 1,863.40. The Nasdaq Composite tumbled 72.777 points or 1.75 percent, to 4,075.561.
For the week, the Dow fell 0.3 percent, the S&P 500 dipped 0.1 percent and the Nasdaq lost 0.5 percent.
While companies are clearing a lowered bar for earnings, estimates have been improving. Profits are now seen rising 3.3 percent this quarter, down from the 6.5 percent growth rate estimated at the start of the year, but above the low of 0.6 percent seen last week, according to Thomson Reuters data.
Healthcare names were among the biggest gainers after LifePoint Hospitals Inc's results. The stock advanced 6.3 percent to $56.87, while Tenet Healthcare jumped 9.1 percent to $46.11 and Community Health climbed 6.6 percent to $39.92.
In the latest economic data, U.S. consumer sentiment rose to a nine-month high in April, according to the Thomson Reuters/University of Michigan index. But the U.S. services sector expanded at a slower rate. 1/2ID:nN9N0MM01U 3/8
Volume was light, with about 5.49 billion shares traded on U.S. exchanges, well below the 6.57 billion average so far this month, according to data from BATS Global Markets.
Declining stocks outnumbered advancing ones on the NYSE by a ratio of 2 to 1, while on the Nasdaq, five stocks fell for every one that rose.
(Editing by Chizu Nomiyama, Nick Zieminski and Jan Paschal)