U.S. stocks were lower on Monday as investors assessed the G20's decision to drop a pledge to keep global trade free and open.
Financial leaders of the world's biggest economies made only a token reference to trade in their communique on Saturday, acquiescing to an increasingly protectionist United States after the two-day meeting failed to yield a compromise.
The dollar fell to a six-week low, while European stocks were lower.
The U.S. stock market has been on a roll since the election of Donald Trump as president as investors bet on his plans to reform the tax code and cut regulation. The S&P 500 has risen about 11 percent since early November.
"Given the slow progress in implementing tax cuts and infrastructure spending plans, markets will soon realize that they are ahead of themselves," said Hussein Sayed, chief market strategist at FXTM.
"I'm still quite confident that U.S. protectionist policies will do more harm than good."
Analysts are also worried that the Trump administration is spending too much of its political capital in an effort to pass a Republican-proposed healthcare bill, which may leave it wanting for support when it tries to reform the tax code.
At 9:37 a.m. ET (1337 GMT), the Dow Jones Industrial Average was down 15.21 points, or 0.07 percent, at 20,899.41.
The S&P 500 was down 4.06 points, or 0.17 percent, at 2,374.19.
The Nasdaq Composite was down 6.97 points, or 0.12 percent, at 5,894.03.
Six of the 11 major S&P sectors were lower, with the energy index's 0.86 percent fall leading the decliners.
The U.S. Federal Reserve's conservative rate guidance is also weighing on investors, who will keep an eye on Federal Reserve Bank of Chicago President Charles Evans' speech later in the day.