A slowdown in a hiring survey gave investors a reason to pause on Wednesday - one day after the S&P 500 closed at a record high.The Dow dropped 323 points. The S&P 500 fell 20. The Nasdaq rose 19.Private hiring in July was the lowest in five months, according to payroll processing company ADP. Economists say the data suggest the labor shortage hasn't gotten better. Some have blamed extra jobless benefits, lack of affordable child care and health fears for keeping potential workers, mostly women, at home.Whatever is behind the slowdown in hiring, the ADP report is causing some concern ahead of Friday's government jobs data, says Randy Warren. He's chief investment officer at Warren Financial."You know, the ADP number is not always a great indicator of what the jobs report is going to be on Friday, but it certainly, you know, 300-and-something-thousand - a little bit worrisome when you're considering that the the anticipated number for Friday is 870,000 or something like that. That's a big number and the market would be very disappointed with the number in the three, four or five handle."Other economic figures were more upbeat. Activity in the vast U.S. services sector sprinted to a record high in July.Earnings were a mixed bag.General Motors posted record pre-tax profits and raised its outlook for the year on the strength of sales of its pick-up trucks. But investors are worried about future impact of the long-lasting chip shortage. Shares of GM slumped nearly 9 percent.Kraft-Heinz beat sales forecasts as eating at home remained strong even though Americans are dining out more. But the maker of ketchup and macaroni and cheese warned it is getting squeezed by higher food costs. The stock fell roughly 5 percent by the closing bell.After the close, Uber posted a much wider-than-expected adjusted quarterly loss.Outside of earnings: Robinhood, which had a dud of an IPO last week, surged on Wednesday as the Reddit crowd stepped in to give the stock meme status. The stock had a one-day rally of 50 percent.