As of midday trading Monday, the was set to log its worst day of the year, as President Donald Trump's brash words and anti-free-trade moves appeared to spook investors.
On Monday morning, Trump signed an executive order withdrawing the U.S. from the Trans-Pacific Partnership, a trade agreement with 11 countries that had yet to be ratified. He is also expected to sign an order stating his intent to renegotiate the North American Free Trade Agreement. And in a meeting with CEOs, he reiterated his plan to impose some sort of tax on goods created outside the United States.
Amid the headlines, the S&P slipped as much as 0.6 percent. While a small move in the scheme of things, that would actually make for the market's largest drop since Dec. 28, when the S&P closed 0.84 percent lower.
"Trump's approach to trade is finally catching up to the market," Max Wolff, market strategist at 55 Capital, told CNBC in a Monday interview.
To Gina Sanchez of Chantico Global, the decline is not about the moves against free trade specifically; rather, "this is a general sense of concern that is driving this move."
After confrontational Trump speeches at his inauguration and at CIA headquarters dampened expectations he would become more temperate postelection, "the markets are starting to get nervous that the first 100 days [of Trump's presidency] are off to a rocky start," she wrote to CNBC.
Boris Schlossberg, macro strategist and trader at BK Asset Management, is of a similar mind, writing on Monday: "Markets have clearly been taken aback by his confrontational style of politics and unless the U.S. economy shows some rapid improvements in growth, the enthusiasm that accompanied Mr. Trump into the office will quickly turn into fear as investors begin to consider the costs of his protectionist policies and bare knuckles style of governing."
Wolff put it a bit more starkly: After a significant rally after Trump's election, "the honeymoon is over, and investors just woke up and took a long look at the bride."
Of course, some context is important. Even at Monday's lows, the S&P is just 1 percent away from its peak.
"What's crazy is that it feels like the world is on the verge of collapse but SPUs are less than 15 handles from the Jan. 6 all-time high," Michael Block, of Rhino Trading Partners, mused in a Monday morning missive.