* Roku tumbles as supply chain issues hit sales
* Monthly options expiry seen adding volatility
Feb 18 (Reuters) - Wall Street ended lower on Friday after escalating tensions in Ukraine and U.S. warnings of a potential Russian invasion prompted investors to dump risky assets in the run-up to a long weekend.
The Nasdaq fell sharply, pulled down by declines in high-growth stocks, including Apple, Amazon and Microsoft, each down around.
Russian-backed separatists packed civilians onto buses out of breakaway regions in east Ukraine, another development in a conflict the West believes Moscow plans to use as justification for all-out invasion of its neighbor. Russia has said it has no intention to attack Ukraine, accusing the West of fear-mongering.
Speculation about the Federal Reserve's next move also weighed on equities. New York Fed Bank President John Williams said earlier in the day it would be appropriate to hike interest rates in March, without mentioning the magnitude.
"This is a confused market, confused about Ukraine, confused about how aggressive the Fed is going to be, and pretty much ignoring very strong earnings results from the fourth quarter," said Tim Ghriskey, senior portfolio strategist at Ingalls & Snyder in New York.
Expiration of monthly options contracts was also seen adding to the volatility ahead of the U.S. market holiday on Monday for Presidents' Day.
The Dow Jones Industrial Average fell 0.68% to end at 34,079.18 points, while the S&P 500 lost 0.72% to 4,348.87.
The Nasdaq Composite dropped 1.23% to 13,548.07.
The indexes logged weekly declines for the second straight week, buffeted by rising tensions between Moscow and the West over Ukraine. For the week, the S&P 500 fell 1.6%, the Dow lost 1.9% and the Nasdaq declined 1.8%.
Intel Corp tumbled 5.3% to its lowest since 2020 after the chipmaker's turnaround pitch failed to impress investors worried about its loss of market share.
About 78% of the 417 S&P 500 companies have in this reporting season posted quarterly earnings above analyst estimates as per Refinitiv data.
Roku Inc slumped 22% after the streaming platform's disappointing quarterly revenue and first-quarter outlook.
DraftKings Inc also fell 22% after the sports-betting company forecast a bigger-than anticipated 2022 loss.
Declining issues outnumbered advancing ones on the NYSE by a 1.84-to-1 ratio; on Nasdaq, a 2.10-to-1 ratio favored decliners.
The S&P 500 posted 8 new 52-week highs and 28 new lows; the Nasdaq Composite recorded 19 new highs and 395 new lows.
Volume on U.S. exchanges was 11.3 billion shares, compared with the 12.3 billion average over the last 20 trading days.