The Dow Jones Industrial Average slipped on Wednesday after private sector hiring hit its lowest level in more than two years, raising concerns trade policy uncertainty could be weighing on the U.S. economy.

The 30-stock Dow lost 91.90 points, or 0.22%, ending at 42,427.74. The blue-chip average snapped a four-day winning run. The S&P 500 advanced 0.01% and closed at 5,970.81, while the Nasdaq Composite rose 0.32% and settled at 19,460.49.

A report from payrolls processing firm ADP showed that payrolls increased only 37,000 for the month, less than the downwardly revised 60,000 in April and below the consensus forecast of 110,000 that economists polled by Dow Jones were expecting.

The report casts a pall over Friday's all-important government nonfarm payrolls report, which economists currently expect to show an increase of 125,000 jobs for May, according to a Dow Jones survey.

President Donald Trump blasted Federal Reserve Chairman Jerome Powell right after those numbers came out, saying "Too Late Powell" should cut rates.

Even with the "volatile" ADP report and tariff overhangs, Mike Dickson of Horizon Investments told CNBC that "things are probably better than feared."

"I think the ADP report has had the history of being quite noisy, so I think we're just going to have to wait and see about Friday as it relates to the labor market," the firm's head of research and quantitative strategies said. "Recent inflation data has been pretty tame and healthy in the right direction."

That said, he still thinks the market is range-bound in the near term, adding that "we're entering into a little bit of a lull" in terms of market catalysts for the next month.

Wall Street is coming off a solid stretch with strong gains in tech stocks allowing investors to look past any worries about tariffs or the economy. The 30-stock Dow rose more than 200 points, or 0.5%, on Tuesday.

The recent gains have investors increasingly confident stocks have turned a corner on tariffs, especially after a series of reversals from Trump convinced traders the White House is mainly wielding high levies as a negotiating tool. A federal court striking down the president's tariffs just last week added to hopes the market has priced in the worst of the duties, though they were later reinstated temporarily by an appeals court.

Trump posted earlier Wednesday that dealing with Chinese President Xi Jinping has been "extremely hard."