The S&P 500 and the Dow Jones Industrial Average slipped on Thursday, after four sessions of gains, over concerns about the US-China trade war, but gains in technology stocks helped lift the Nasdaq.
Washington has proposed slapping tariffs on a further $200 billion worth of Chinese goods, which will come into effect next month after a public comment period ends on Wednesday, Sept. 5.
Metal prices fell as the Sino-US trade tensions upstaged optimism that the United States and Canada could clinch a new North American Free Trade Agreement (NAFTA).
The S&P materials index sank 1.27 percent, the most among the 11 major S&P sectors. Trade-sensitive industrials fell 0.5 percent, led by Caterpillar's 1.2 percent decline.
However, high-profile technology stocks provided support. Facebook was up 2 percent and Apple rose 1.4 percent.
Amazon rose as much as 1.4 percent to a record high of $2,025.57, moving closer to joining Apple in the $1 trillion market cap club. Amazon was last up 1.3 percent.
"I would never bet against the tech leaders, because every single time the markets have ticked down the tech stocks seemed to have eventually gained enough to close the markets higher and today should be no different," said Brad McMillan, chief investment officer at Commonwealth Financial Network in Waltham, Massachusetts.
At 12:49 p.m. ET the Dow Jones Industrial Average was down 87.09 points, or 0.33 percent, at 26,037.48, the S&P 500 was down 5.79 points, or 0.20 percent, at 2,908.25 and the Nasdaq Composite was up 10.08 points, or 0.12 percent, at 8,119.77.
The declines come after a four-day run of record gains for the S&P 500 and the Nasdaq.