The Dow Jones Industrial Average erased 95.70 points, or 0.36 percent, to 26,478.02. The S&P 500 decreased 13.22 points, or 0.45 percent, to 2,938.79. The Nasdaq Composite Index was down 26.18 points, or 0.33 percent, to 7,956.29.
Ten of the 11 primary S&P 500 sectors closed lower, with energy down 0.92 percent, becoming the worst-performing group. Communication services rose a modest 0.04 percent, the only gainer.
Investors are awaiting the U.S.-China trade talks which are set to begin later this week.
"The effects of the existing trade taxes are seen in investment spending. Companies are less likely to invest when the supply chains that have been built up over thirty years are being threatened," analysts at Swiss investment bank UBS said in a note on Monday.
Wall Street is also expecting Federal Reserve Chairman Jerome Powell's upcoming speech at the U.S. National Association for Business Economics annual meeting.
Last week, a flurry of weak U.S. data raised hope for easier monetary policy from the Federal Reserve.
Market expectations for a rate cut later this month were more than 70 percent, according to the CME Group's FedWatch tool.