DETROIT – So what's making the stock market – and maybe even your 401(k) – a bit sick?

Did stocks tumble Monday on news that the much-feared new coronavirus has already killed more than 80 people in China? Or were investors fearful of the possible unleashing of new damaging details in the impeachment trial of President Donald Trump?

Take your pick. Wall Street could very well see wild swings in the days ahead regarding developments in both of these major news stories.

The reality is that we've had quite a run up in stock prices, as the Dow broke one record after another in recent weeks. The Dow reached a record 29,348.10 points on Jan. 17. Any sudden turns or threats along the way here could drive some pullback in stock prices at the very least.

A worse-than-expected turn or shock would create more lasting damage.

The Dow Jones Industrial Average fell by more than 500 points in morning trading and closed at 28,535.80 points on Monday, down 453.93 points or 1.57%.

Michigan has its eye on both of the big headlines.

Michigan is a battleground state for the Trump reelection bid in 2020. On Thursday, Trump will head to Dana Inc., an auto parts supplier in Warren, to talk up the U.S. Mexico Canada Trade Agreement.

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This week, Trump's team is out to both downplay the ongoing impeachment trial and an exclusive New York Times report published Monday detailing a claim by former National Security Adviser John Bolton that Trump explicitly linked a freeze on $391 million in security assistance to Ukraine to an investigation of Democrats, including presidential hopeful and former Vice President Joe Biden.

According to The New York Times, an unpublished manuscript by Bolton "presents an outline of what Mr. Bolton might testify to if he is called as a witness in the Senate impeachment trial."

Wall Street in general has favored many of the economic and tax policies initiated by the Trump administration. Business leaders and owners are far more skeptical and wary for the most part about political promises by Democratic hopefuls Sen. Elizabeth Warren and Sen. Bernie Sanders to undo Trump tax cuts among other changes.

Michigan's auto industry must keep its eye on the spread of coronavirus, too, given its interest and manufacturing operations in China.

David Whiston, equity strategist tracking U.S. Autos for Morningstar Research Services, said it's difficult to predict the exact impact of the coronavirus on the auto industry because no one knows how long the epidemic will last.

"Any automaker with meaningful China results will take a hit and GM is one of the biggest firms in the market," Whiston said.

"Ford is trying to turn around its China operations so this does not help either."

Whiston noted that the spread of the virus has been happening during the Chinese New Year, when consumers may not be normally buying vehicles in large volume anyway.

"As long as this does not last many months, a sell-off in the stocks is a buying opportunity in my opinion," Whiston said.

Wall Street recognized the risks that GM has in China, and drove GM's stock price down Monday more than Ford.

General Motors stock closed Monday at $33.41 a share, down 90 cents or 2.62%

Ford stock closed Monday at $8.89 a share, down 11 cents or 1.22%.

Fiat Chrysler Automobiles close at $13.07 a share, down 28 cents or 2.1%.

Many market watchers aren't expecting the U.S. economy to take a significant hit as a result of the impeachment hearings – since the GOP controls the Senate – or the coronavirus.

Robert Bilkie, CEO of Sigma Investment Counselors in Northville, said he would look for continued weakness in stock prices as the two situations unfold, but in general he views downturns in stock prices at this point as buying opportunities.

Again, though, much will depend on the potential twists ahead.

"Stock investors are nervous about the coronavirus because of the considerable uncertainty over how broadly across the globe it will spread, and how disruptive it will be to the fragile Chinese economy where the virus is already a problem," said Moody's economist Mark Zandi.

Stock prices have had a strong run-up since Trump called a truce in his trade war with China. The theory is that the Chinese economy would be less vulnerable and could rebound.

"The coronavirus threatens to undermine any revival in the Chinese and global economies," Zandi said.

Investors also may react negatively to such news as the coronavirus because stocks have been exceptionally strong of late.

"Stock prices reflect nothing but good news, and the coronavirus is bad news," Zandi said.

Contact Susan Tompor: 313-222-8876 or stompor@freepress.com. Follow her on Twitter @tompor. Read more on business and sign up for our business newsletter.

This article originally appeared on Detroit Free Press: Uncertainty unfolds on Wall Street regarding coronavirus, impeachment