The major U.S. indexes slid Thursday as an unexpected decline in jobless claims renewed concerns that labor-market strength would push up interest rates.

The blue-chip Dow Jones Industrial average plunged as much as 600 points, or 2.4 percent, in early afternoon trading in New York, while the broader S&P 500 dropped 2.1 percent and the tech-heavy Nasdaq slid 2.4 percent.

Initial claims for unemployment benefits in the week through Feb. 3 dropped 4 percent to 221,000, lower than the estimate of 235,000 from British lender Barclays Plc, while the four-week average dipped to 224,500. That‘s the lowest since 1973, the Department of Labor said Thursday.

The market’s reaction mirrored its response to broader employment data released on Friday, which sparked worries that strong employment and faster economic growth would prompt the Federal Reserve to raise interest rates more quickly.

The central bank has increased short-term rates just five times since they were cut to nearly zero during the 2008 financial crisis, taking them to a range of 1.25 to 1.5 percent.

That benefits banks, which usually pass increases on to borrowers more quickly than lenders, but it’s unwelcome news for both consumers with high credit-card debt and heavily-leveraged corporations.

The U.S. economy’s fundamental strength, however, bodes well for markets, investors say.

“This feels a lot more to me like a normal correction in what could be a pretty good year for the stock market,” Wayne Wicker, who oversees $51 billion in public-employee retirement assets as chief investment officer for ICMA-RC, told the Washington Examiner on Wednesday after a volatile start to the week.

Still, he said, “I’d be reluctant to ring the all-clear button at this point because February’s typically a pretty volatile month.”

As for President Trump — who frequently cited meteoric gains that drove the Dow Jones 25 percent higher in 2017 as proof his policies were working — he considers the February selloff to be simply poor strategy.

“Big mistake, and we have so much good (great) news about the economy,” he wrote in a post on Twitter.