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* China trade deal signing expected soon - White House adviser
* Tesla rival Nio jumps after strong quarterly sales
* Energy sector up on higher oil prices
* Dow Jones on track for worst day in three weeks
* Indexes down: Dow 0.32%, S&P 0.34% , Nasdaq 0.48% (Updates comment, prices)
By Manas Mishra
Dec 30 (Reuters) - U.S stock indexes slipped from record highs on Monday as investors booked profits on the penultimate day of the decade after optimism over improving U.S.-China trade relations fueled a Wall Street rally this month.
White House Trade Adviser Peter Navarro said on Monday the pact was likely to be signed in the next week, but added that confirmation would come from President Donald Trump or the U.S. Trade Representative.
A South China Morning Post report earlier said Chinese Vice Premier Liu He would travel to Washington later this week to sign the deal.
The benchmark S&P 500 closed at all-time highs in nine of the past 11 sessions, also powered by improving global sentiment and a loose monetary policy by the Federal Reserve.
But with no other major updates on trade expected before the new year and thin trading volumes in a holiday-shortened week, some analysts expect the record run to lose steam further.
"There's just not a whole lot going on. Traders are trying to think about how they want to position for next year," said Sahak Manuelian, head of equity trading at Wedbush Securities.
The Nasdaq fell for the second straight session, after having snapped an 11 session winning streak on Friday.
Tech stocks largely led the drop in the S&P 500, with Microsoft Corp weighing on the sector. Information technology stocks were the best performing among the 11 S&P 500 subsectors this year.
"It is ... not uncommon for the leading sectors to pull back first when people start to sell because if it is an outperformer, then it warrants a lot more downside risk," said Randy Frederick, vice president of trading and derivatives for Charles Schwab in Austin, Texas.
Energy was one of the two S&P 500 sectors in the black, tracking higher oil prices.
At 12:34 p.m. ET, the Dow Jones Industrial Average was down 92.76 points, or 0.32%, at 28,552.50, the S&P 500 was down 10.98 points, or 0.34%, at 3,229.04. The Nasdaq Composite was down 43.57 points, or 0.48%, at 8,963.05.
Nio Inc soared 60.5% after the Tesla rival beat quarterly revenue estimates on higher demand for its electric vehicles.
Declining issues outnumbered advancers for a 1.14-to-1 ratio on the NYSE and a 1.20-to-1 ratio on the Nasdaq.
The S&P index recorded 12 new 52-week highs and no new low, while the Nasdaq recorded 56 new highs and 22 new lows. (Reporting by Manas Mishra in Bengaluru; Editing by Maju Samuel, Shinjini Ganguli and Shounak Dasgupta)