The numbers: The number of Americans who applied for unemployment benefits in the week before Thanksgiving rose to the highest level in 4½ months, potentially adding to fresh worries about the U.S. economy.

Initial jobless claims, a rough way to measure layoffs, rose by 3,000 to 224,000 in the seven days ended Nov. 17. That was well above than the 215,000 forecast of economists polled by MarketWatch.

In an unusual twist, the prior week’s estimate of new claims was raised by 5,000 to 221,000. Rarely is the weekly number revised so sharply.

The monthly average of new claims also increased by 2,000 to 218,500.

What happened: New jobless claims hit the highest level since June 30 and broke a string of 18 straight weeks below 220,000. An official at the Labor Department could not cite any specific factors for the recent increase, though claims do get erratic during the holiday season.

Layoffs are still quite low, however.

The number of people already collecting unemployment benefits, meanwhile, dipped by 2,000 to 1.67 million. These so-called continuing claims are at the lowest level since the early 1970s.

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Big picture: The shocking decline in the stock market this weeks suggests investors are more worried about the future of the economy. The rise in jobless claims and a soft reading on business investment in October are likely to add to the worries.

By most measures, though, the economy still appears to be in good shape. The U.S. labor market is the strongest in decades and most households are in the best financial shape in years. Unless they dramatically cut spending, the economy should continue to grow well into next year.

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What they are saying?: “Broadly, the economy remains on a solid footing in the final weeks of 2018, but some relative weakness in recent data has not been lost on investors,” said Jim Baird, chief investment officer at Plante Moran Financial Advisors

Market reaction: The Dow Jones Industrial Average DJIA, +0.19% and the S&P 500 SPX, +0.29% opened higher in Wednesday trades after a pair of brutal selloffs this week erased all stock-market gains for 2018. Yet a mediocre durable-goods report, an increase in jobless claims and a softer sentiment survey could limit the gains.