CORRECTED: Wall St posts slight gain, investors anxious on Trump-Xi meet

(Corrects paragraph 11 to say trillion, not billion)

By Sinead Carew

REUTERS - Wall Street's major indexes closed slightly higher on Thursday but finished well off session highs as investors were nervous about upcoming talks between China's President Xi Jinping and U.S. President Donald Trump.

The leaders of the world's two biggest economies are to greet each other at the president's Mar-a-Lago retreat in Palm Beach, Florida, late Thursday afternoon, kicking off a summit that will conclude with a working lunch on Friday.

Investors are anxious for news on China-U.S. trade relations and discussions on reining in North Korea's arms program, according to market participants.

"People are concerned because this could go south in a hurry because the Chinese president is a savvy politician with a lot of experience in these types of things and you have a novice (U.S.) politician on the world stage," said Peter Costa, President, Empire Executions Inc in New York.

"The meeting is going to set the tone for what comes ahead and you don't want the tone to be negative," said Costa.

Stocks pared gains in the late afternoon after U.S. Secretary of State Rex Tillerson made comments on the meeting.

From Mar-a-Lago, Tillerson said the United States will "pursue economic engagement with China that prioritizes the economic wellbeing of the American people" and would not shy away from frank discussions.

"Tillerson sounded like he was taking a little bit of a hardline stance with China," said Brian Jacobsen, chief portfolio strategist at Wells Fargo Funds Management in Menomonee Falls, Wisconsin. "This increases the risks that this could be a bit more confrontational than a friendly get-together between Presidents Trump and Xi."

The Dow Jones Industrial Average closed up 14.8 points, or 0.07 percent, to close at 20,662.95, the S&P 500 gained 4.54 points, or 0.19 percent, to 2,357.49 after reaching a session high of 2364.16 earlier in the day.

The Nasdaq Composite added 14.47 points, or 0.25 percent, to 5,878.95.

The stock market had dramatically reversed course to close lower on Wednesday after signals that the Fed would start to trim its $4.5 trillion balance sheet this year.

But investors reconsidered their reactions on Thursday, according to Stephen Massocca, Senior Vice President at Wedbush Securities in San Francisco.

"The Fed isn't going to be indiscriminately pulling the prop out from under the market. There will be some sensitivity to what's going on in the economy," said Massocca.

Four of the 11 major S&P sectors ended lower. The energy index rose 0.8 percent as oil prices rose to near one-month highs. [O/R] Comcast Corp was the S&P's biggest boost with a 2.1 percent gain to $38.13 after it announced a wireless service.

Some investors are cautious ahead of the start of the corporate earnings season next week given the lofty valuations. The S&P 500 index is trading at about 18 times forward earnings estimates, above its long-term average of 15.

Advancing issues outnumbered declining ones on the NYSE by a 3.20-to-1 ratio; on Nasdaq, a 2.18-to-1 ratio favored advancers.

The S&P 500 posted 8 new 52-week highs and four new lows; the Nasdaq Composite recorded 32 new highs and 61 new lows.

About 6.4 billion shares changed hands on U.S. exchanges compared with the 6.8 billion average for the last 20 sessions.

(Additional reporting by Rodrigo Campos in New York and Yashaswini Swamynathan in Bengaluru; Editing by Savio D'Souza and James Dalgleish)