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* Trump threatens new tariffs on Chinese goods next week - report
* Canada, U.S. may not reach NAFTA deal within deadline - report
* Coca-Cola up on plans to buy coffee chain Costa
* Ulta Beauty drops on bleak profit forecast
* Futures down: Dow 0.25 pct, S&P 0.20 pct, Nasdaq 0.11 pct (Changes comments, updates prices)
By Shreyashi Sanyal
Aug 31 (Reuters) - U.S. stock index futures pointed to a lower open on Friday, ahead of the long holiday weekend, with investors wary after President Donald Trump's latest salvo in Washington's trade war with China.
The main indexes snapped a four-day winning streak on Thursday after Bloomberg reported Trump was ready to impose tariffs on $200 billion more of Chinese goods next week, sooner than many expected, when a public comment period on the plan ends.
Adding to the worries, Canadian government officials have expressed concern that a final North American Free Trade Agreement (NAFTA) pact will not be reached within the Friday deadline set by Trump, according to a Globe and Mail report.
"If you combine the tariff issues and the fact that we have a three day weekend, it's more than enough to push the futures down as much as we are seeing right now," said Randy Frederick, vice president of trading and derivatives for Charles Schwab in Austin.
Traders also cautioned markets could be susceptible to bigger-than-usual gyrations as trading volumes are expected to be light ahead of the long Labor day holiday weekend.
At 8:47 a.m. ET, Dow e-minis were down 64 points, or 0.25 percent. S&P 500 e-minis were down 5.75 points, or 0.20 percent and Nasdaq 100 e-minis were down 8.75 points, or 0.11 percent.
Shares of Coca-Cola rose 0.2 percent after the company said it would buy coffee chain Costa for $5.1 billion. Starbucks fell 1.6 percent.
Lululemon was up 10.6 percent after the Canadian athletic apparel maker posted a second-quarter profit that beat estimates on strong online sales, particularly in China.
However, beauty products retailer Ulta Beauty dropped 2.5 percent after the company projected a disappointing current-quarter profit forecast.
Apple gained 0.6 percent. Warren Buffett said Berkshire Hathaway had added to its stake in the iPhone maker and Apple announced a Sept. 12 event, at which it is expected to unveil new iPhone models.
Amazon.com was up 0.3 percent, topping $2,000 for the second day in a row to renew its push to join Apple in the $1 trillion market cap club.
The University of Michigan's consumer sentiment index for August is expected at 10 a.m. ET. (Reporting by Shreyashi Sanyal in Bengaluru; Editing by Shounak Dasgupta)