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* Fed's rate-setting meeting underway
* Trump fires new warning at China
* P&G rises on quarterly profit beat
* Under Armour slides on N.America rev forecast cut
* Indexes off: Dow 0.23%, S&P 500 0.38%, Nasdaq 0.34% (Updates to early afternoon)
By Shreyashi Sanyal
July 30 (Reuters) - U.S. stocks slid on Tuesday after a fresh warning from President Donald Trump to China pressured technology shares, while investors speculated the scale of an interest rate cut at the end of the Federal Reserve's policy meeting.
Apple Inc's results after markets close will paint a clear picture of the impact of trade tensions with China. Shares of the iPhone maker fell 0.76%, contributing the most to the tech sector's 0.64% drop.
"Investors are very concerned about how weak Apple's Chinese business will do," said Tony Roth, chief investment officer at Wilmington Trust in Wilmington, Delaware.
As trade talks between the world's two biggest economies resumed on Tuesday, Trump warned China against trying to wait out his first term in office to finalize a deal.
Market participants are now bracing for what message the Fed will send if it pushes ahead with a well-telegraphed move to ease policy that has driven Wall Street's main indexes to record highs in the past few weeks and contributed to the S&P 500 index's 20% gain for the year.
With a quarter-percentage-point cut in rates at the end of the meeting on Wednesday fully priced-in, investors will monitor how Fed Chairman Jerome Powell manages debate about whether the stimulus is necessary and what that says about the attitude of the U.S. central bank to doing more in the months ahead.
"The Fed has a very strong rationale for cutting interest rates, that is to stimulate growth and inflation, but policymakers have to resort to justifications to keep the expansion going," Roth said.
Corporate earnings so far have been robust. With half of all S&P 500 companies reporting second-quarter results, about 76% have topped profit estimates, according to Refinitiv data.
Backing the case further for a reduction in borrowing costs was data from the Commerce Department that showed U.S. consumer spending and prices rose moderately in June, pointing to slower economic growth and benign inflation.
The Dow Jones Industrial Average fell 62.54 points, or 0.23%, to 27,158.81, the S&P 500 lost 11.35 points, or 0.38%, to 3,009.62. The Nasdaq Composite dropped 28.52 points, or 0.34%, to 8,264.81.
Limiting losses on the blue-chip Dow index was Procter & Gamble Co, which jumped 4.41% after the consumer goods maker beat estimates for quarterly revenue.
The financials sector fell 0.56%, hit by a decline in shares of Capital One Financial Corp after the credit-card issuer said information for 106 million people had been compromised.
Bank stocks, which tend to benefit from a rising interest rate environment, dropped 0.26%.
Pfizer Inc's 6.10% tumble weighed the most on the healthcare index. A couple of brokerages downgraded the stock after the drugmaker said on Monday it would spin off its off-patent drugs unit and merge it with Mylan.
Under Armour Inc slipped 11.84% after the sportswear maker cut its full-year revenue forecast for North America, its biggest market.
Declining issues outnumbered advancers for a 1.04-to-1 ratio on the NYSE. Advancing issues outnumbered decliners by a 1.44-to-1 ratio on the Nasdaq.
The S&P index recorded 27 new 52-week highs and one new low, while the Nasdaq recorded 52 new highs and 75 new lows. (Reporting by Shreyashi Sanyal and Karina Dsouza in Bengaluru; Editing by Sriraj Kalluvila and Maju Samuel)