US STOCKS-Futures fall as Ukraine offsets Microsoft
* Major indexes on track for second week of gains
* Microsoft shares rise after results, Amazon down
* Investors concerned over fallout to Ukraine violence
* Futures down: Dow 33 pts, S&P 4.8 pts, Nasdaq 13.25 pts
By Ryan Vlastelica
NEW YORK, April 25 (Reuters) - U.S. stock index futures edged lower on Friday as intensifying violence in Ukraine and weakness in Amazon.com overshadowed positive results from Microsoft Corp.
* In the latest sign of ongoing geopolitical strife, Ukrainian forces killed up to five pro-Moscow rebels and Russia launched army drills near the border in response, raising fears its troops would invade. Separately, local police said seven people were injured overnight at a pro-Ukrainian checkpoint near the Black Sea port of Odessa when an explosive device blew up.
* While the situation has taken a backseat to corporate earnings in recent weeks, investors remain on edge over what the potential fallout could be to any prolonged tension or violence.
* Amazon fell 2 percent to $330.25 after posting a jump in revenue that was offset by sharp increases in spending. On the upside, Microsoft's earnings topped analyst forecasts, while investors were cheered by the software giant's new emphasis on mobile and cloud computing. Shares rose 1.7 percent to $40.52. Continuación...