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* Futures down: Dow 0.48%, S&P 0.45%, Nasdaq 0.59%
* China unveils retaliatory tariffs on U.S. goods
* Powell's speech to start at 10:00 a.m. ET
* HP Inc falls after CEO exit, disappointing forecast
* Foot Locker slumps after quarterly results miss estimates (Changes comment, adds details; Updates prices)
Aug 23 (Reuters) - Wall Street was set to open lower on Friday as China's threat to impose tariffs on $75 billion worth of U.S. goods ratcheted up trade tensions ahead of a highly anticipated speech by Federal Reserve Chair Jerome Powell.
China's commerce ministry said it would impose additional tariffs on a total of 5,078 U.S. products that include agricultural products, crude oil, small aircraft and cars. Tariffs on some products would take effect on Sept. 1 and others on Dec. 15.
Shares of oil majors Exxon Mobil Corp and Chevron Corp fell more than 1% in premarket trading, while those of carmakers General Motors Co and Ford Motor Co dropped about 2%. Business jets maker Textron Inc was down 3.3%.
"Of course China is going to retaliate. That is part of the trade war," said Scott Brown, chief economist at Raymond James, in St. Petersburg, Florida.
"Trade issues are going to be important heading into the Powell speech and he has to give some indication on how the global environment is influencing the Fed."
Powell speaks at 10 a.m. ET (1400 GMT) in Jackson Hole and investors will be looking for confirmation that the central bank will cut interest rate next month against the backdrop of increasing risks for the economy, especially from the ongoing trade war.
The minutes of the Fed's meeting in July, issued earlier this week, showed policymakers were in doubt about whether a new cycle of rate cuts was justified.
Investors are hoping Powell will sound more convinced when he speaks although most analysts were playing down the chance of a strong commitment on more cuts.
At 8:41 a.m. ET, Dow e-minis were down 126 points, or 0.48%. S&P 500 e-minis were down 13.25 points, or 0.45% and Nasdaq 100 e-minis were down 45.75 points, or 0.59%.
After three straight week of declines, the main Wall Street indexes are on course to end the week higher thanks to signs that U.S. consumer demand remains strong.
Also crucial to the positive mood this week is the assumption that the Fed and other central banks, as well as some governments, are ready to take more action to stave off any risk of a slide into recession in the months ahead.
HP Inc slipped 9.2% after Chief Executive Officer Dion Weisler stepped down and the PC maker forecast fourth-quarter profit below analysts' estimates.
Foot Locker Inc tumbled 12.4% after the footwear retailer missed estimates on second-quarter revenue and profit. The disappointing earnings also pulled shares of Nike Inc , its major supplier, down 0.8%.
In a bright spot, Salesforce.com Inc gained 6.2% premarket after cloud-based service provider forecast third-quarter and full-year revenue above Wall Street estimates. (Reporting by Akanksha Rana, Amy Caren Daniel and Medha Singh in Bengaluru Editing by Saumyadeb Chakrabarty)