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* Fed policy meeting to start on Tuesday
* U.S.-China trade negotiators meet in Shanghai
* Mylan to combine with Pfizer's off-patent drugs unit
* Dow up 0.17%, S&P 500 off 0.19%, Nasdaq down 0.57% (Updates to late afternoon, changes dateline, byline)
By Stephen Culp
NEW YORK, July 29 (Reuters) - U.S. stocks backed away from record highs on Monday as investors looked forward to an interest rate cut from the U.S. Federal Reserve and for signs of progress from Shanghai, where U.S.-China trade negotiations are underway.
Amazom.com Inc and Facebook Inc weighed heaviest on the S&P 500 and the Nasdaq after the indexes ended last week at new closing peaks.
Market participants girded themselves for an eventful week, with the FOMC meeting, ongoing U.S.-China trade talks and nearly a third of the companies in the S&P 500 reporting second-quarter results.
The Fed, watchful of languid inflation and signs of economic softness arising from tariff disputes, is expected to lower interest rates for the first time in a decade at the conclusion of its two-day monetary policy meeting, which convenes on Tuesday.
"The Fed announcement is going to be key, especially the Fed outlook," said Tim Ghriskey, chief investment strategist at Inverness Counsel in New York.
The central bank is "beginning to accept the idea that the success of these (U.S.-China trade) negotiations will be modest at best and will cut rates in order to perpetuate the economic expansion," Ghriskey added.
U.S. negotiators are meeting their Chinese counterparts in Shanghai this week in an effort to find a path toward resolving the long-running, market-rattling trade war between the world's two largest economies.
The Dow Jones Industrial Average rose 46.69 points, or 0.17%, to 27,239.14, the S&P 500 lost 5.85 points, or 0.19%, to 3,020.01 and the Nasdaq Composite dropped 47.21 points, or 0.57%, to 8,283.00.
Nine of the 11 major sectors in the S&P 500 were in the red, with consumer discretionary and communications services seeing largest percentage losses.
With second-quarter earnings season approaching the halfway mark, 76.1% of companies having reported have beaten consensus estimates, according to Refinitiv data.
"There have been a lot of positive surprises, so while we may end up with a negative quarter, overall it won't be as bad as feared," Ghriskey said.
Mylan NV's shares jumped 12.5% after the generic drugmaker confirmed reports that it was combining with Pfizer Inc's Upjohn unit that sells its off-patent branded medicines, a move that brings blockbuster treatments Viagra, EpiPen and Lipitor under one umbrella.
Pfizer shares slipped 2.1% after the company lowered its full-year profit and revenue forecasts in an earlier-than-expected release of its quarterly results timed to go with the deal announcement.
Ride-hailing company Lyft Inc dipped 2.3% as CNBC reported Chief Operating Officer Jon McNeill is leaving.
Starbucks Corp fell below Friday's record high, dropping 1.3% after J.P.Morgan downgraded the coffee chain's stock to "neutral," saying its valuation has become "beyond stretched."
Declining issues outnumbered advancing ones on the NYSE by a 1.11-to-1 ratio; on Nasdaq, a 1.56-to-1 ratio favored decliners.
The S&P 500 posted 35 new 52-week highs and 3 new lows; the Nasdaq Composite recorded 59 new highs and 94 new lows. (Reporting by Stephen Culp Editing by Bill Berkrot)