The S&P 500 and the Dow Jones Industrial Average gave up all gains on Tuesday, reversing from a strong start on the back of progress in U.S.-China trade talks, as President Donald Trump threatened to shut down the federal government over funding for a wall along the U.S.-Mexico border.
At 12:17 p.m. ET, the Dow Jones Industrial Average was down 71.95 points, or 0.29 percent, at 24,351.31. The S&P 500 was down 0.90 points, or 0.03 percent, at 2,636.82 and the Nasdaq Composite was up 15.82 points, or 0.23 percent, at 7,036.34.
Day earlier, US stocks rose for the second straight day, led by technology companies on signs that China and the United States were moving toward resolving their bitter trade dispute that has roiled global equities markets for months.
After a strong start, which was also boosted by healthy economic data, the three indexes pared gains to about 0.5 percent, helping the S&P 500 and Dow Jones Industrial Average cut some of their losses for the year.
US and Chinese officials discussed a road map for the next stage of trade talks, while President Donald Trump said negotiations were "very productive" and an "important announcement" was imminent.
Adding to the optimism was a Bloomberg report that China is moving to cut import tariffs on US-made cars to 15 percent from 40 percent, which lifted shares of General Motors Co and Ford Motor Co.
"The trade headlines help, but there is something being said for a new market structure where a lot of money is managed passively by algorithms driven accounts," said Yousef Abbasi, global market strategist at INTL FCStone in New York.
The trade-sensitive chipmakers index jumped 1.61 percent, while industrials rose about 0.13 percent. Pfizer Inc was down 1.67 percent after a JP Morgan downgrade. Apple Inc was off 0.28 percent, while Boeing Co reversed course to drop 0.8 percent. The three stocks curtailed gains on the indexes.