By Manas Mishra

Dec 26 (Reuters) - The Nasdaq breached the 9,000-point mark for the first time and the S&P 500 hit a fresh record high on Thursday, boosted by optimism over U.S.-China trade relations and gains in Amazon.com after a report signaled robust online holiday sales.

Shares of the retail giant AMZN.O rose 2.5% after Mastercard's report showed U.S. shoppers spent more online during the holiday shopping season, with e-commerce sales hitting a record high.

Gains in Amazon lifted the consumer discretionary index .SPLRCD by 0.7%, the most among the 11 S&P 500 sectors.

"The important part is that the online sales were much stronger than expected. The brick and mortar were less than expected, so the online sales, and principally Amazon, saved the day," said John Conlon, director, equity strategy at People's United Advisors in Bennington, Vermont.

Traders returned from the Christmas break to Beijing's reaffirmation that it was in close contact with Washington about the initial agreement, which is widely expected to be signed in early January.

President Donald Trump on Tuesday confirmed that the pact would be formalized at a signing ceremony, but did not disclose a date or location.

"If the U.S.-China trade agreement can be signed, and we move forward, that would help long term global growth," Conlon said.

Hopes of a breakthrough in the prolonged trade war, combined with a loose monetary policy and robust domestic data, have powered U.S. stocks to record highs in the past few weeks.

The S&P 500 is about one percentage point short of its best year since 1997.

At 11:26 a.m. ET, the Dow Jones Industrial Average .DJI was up 80.77 points, or 0.28%, at 28,596.22, the S&P 500 .SPX was up 11.65 points, or 0.36%, at 3,235.03. The Nasdaq Composite .IXIC was up 47.21 points, or 0.53%, at 9,000.10.

Trading volumes are expected to remain thin this week.

A Labor Department report on Thursday showed that the number of Americans filing for unemployment benefits fell last week, indicating resilience in the labor market.

The energy sector .SPNY gained 0.6%, supported by higher oil prices. O/R

Tesla Inc TSLA.O shares edged up 1.7% as Wedbush boosted its price target on the electric-car maker's stock, partly on expectations of strong U.S. demand for the Model 3 sedans.

Advancing issues outnumbered decliners by a 2.09-to-1 ratio on the NYSE and by a 1.38-to-1 ratio on the Nasdaq.

The S&P index recorded 22 new 52-week highs and no new lows, while the Nasdaq recorded 93 new highs and 16 new lows.

(Reporting by Manas Mishra in Bengaluru; Editing by Anil D'Silva and Arun Koyyur)

((Manas.Mishra@thomsonreuters.com; within U.S. +1 646 223 8780, outside U.S. +91 806749 8325;))

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