Markets Are Already Volatile. A Long Shutdown Could Make It Worse.

While first effects of government shutdown are negligible, a prolonged stalemate could rattle business confidence

A sign alerts visitors to the closure of the National Archives in Washington on the fifth day of a partial government shutdown on Wednesday. Photo: jim lo scalzo/epa-efe/rex/Shutterstock

WASHINGTON—A short government shutdown would likely have little impact on the overall U.S. economy, but a protracted budget fight during a time of heightened stock market volatility could worsen an already murky outlook, economists say.

The partial U.S. government closure entered its sixth day Thursday as President Trump and Congress remained at an impasse over his demand for more funding for a border wall, leaving 800,000 federal workers furloughed or working without pay.

The initial economic effects are likely negligible, despite the hardships for individual employees, because the shutdown initially fell on two weekend days and two federal holidays and affected about a quarter of government offices.

Moreover, much of the suspended federal spending would likely be shifted into the new year, if recent precedent holds. Congress in the past has voted to give furloughed workers back pay once funding is restored, though this isn’t guaranteed. Essential workers who remain on the job will eventually get paid, but not until the shutdown ends.

President Trump on Tuesday criticized the Federal Reserve's interest-rate increase and insisted that the partial government shutdown wouldn't end until Congress funds a wall along the border with Mexico. Photo: Getty Images

The danger, analysts said, lies in the prospect of a prolonged stalemate, coming at a time when investors and businesses are already jittery over multiple factors, including U.S.-China trade tensions, rising U.S. interest rates, the decline in stock prices and slowing global economic growth.

“What would be worrisome is if businesses start to lose confidence” in the government, said Kathy Bostjancic, head U.S. financial market economist at Oxford Economics. “They’ll pull back on hiring and investment, and it’ll become a self-fulfilling prophecy, where negativity in the stock market turns to negativity in the [broader] economy.”

Fresh data released Thursday morning show the job market is likely to remain on a solid footing in the near future. Jobless claims, a leading indicator of the economy’s future trajectory, ticked down last week. The measure gauges the number of Americans filing applications for new unemployment benefits.

Still, the recent stock market rout appears to be weighing on Americans: a gauge of consumer confidence fell for the second month in a row in December.

S&P estimates this shutdown—the third this year—could shave $1.2 billion off U.S. gross domestic product for each full workweek it continues, a relatively small hit in a roughly $20 trillion economy.

Historically, shutdowns haven’t significantly affected economic output. Despite the first two shutdowns this year—each lasting less than four days—growth later accelerated and the unemployment rate fell to historic lows, propelled in part by tax cuts and an agreement to boost federal spending.

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An October 2013 shutdown lasted for more than two weeks, and still the economy grew in the fourth quarter of that year at the strongest pace in two years. The story was similar in 1995, which saw two shutdowns of less than a week each.

Many forecasters already expect the U.S. economy’s growth to slow in 2019, though to a still solid pace, partly due to the waning stimulus from the tax cut and spending increase.

They worry, however, that the risks to the outlook rise if the shutdown continues into 2019 and becomes harder to resolve, with the Democrats taking control of the House of Representatives Jan. 3 and Republicans retaining control of the Senate.

A protracted “federal shutdown would compound the effects of fading fiscal stimulus and act as a drag on an economy already experiencing decelerating growth,” said Beth Ann Bovino, U.S. chief economist at S&P.

Another concern is that an extended budget showdown and hardened gridlock could make it difficult for the White House and Congress to agree to raise the federal borrowing limit, or debt ceiling, next year. Without such an agreement, the government would be unable to pay all its bills, potentially shaking markets and hurting the economy.

The shutdown “just increases concerns of stability,” Ms. Bostjancic said. “There are big questions about how we govern going forward.”

Write to Sharon Nunn at sharon.nunn@wsj.com