By the market close on Monday, the S&P 500 was down 111.85 (3.4%), Dow Jones Industrials was off 1,031.40 (3.6%), the Nasdaq was down 355.31 (3.7%), and the Russell 2000 had dropped 48.81 (2.9%).

Though a 3% drop is certainly unnerving for investors, a retreat of that magnitude is actually more common than many might assume, as the table below shows.

The biggest loss, of course, came on Oct. 19, 1987, known as Black Monday, which saw the Dow fall 22.6% and the S&P 500 lose 20.4%. While today doesn’t compare, Monday’s trading still wiped out all the year’s gains for the S&P 500, Dow, and Russell 2000. Only the tech-heavy Nasdaq kept any growth, and that was cut to 2.8% for the year.

“I do believe [the drop is] the concern of just how much this is going to clip global growth,” said Jamie Cox, managing partner at Harris Financial Group. “The bond market has been pricing this in for a couple of weeks now.” Not all sectors were hit equally: while the energy sector of the S&P 500 fell 4.7%, real estate was only off 1.3%.

For weeks equities had seemed to shrug off the economic germaphobia for a few reasons. One, according to Cox, was because of the strength in tech stocks. “When the majority of your stock indexes have tech stocks, it’s easy for them to mask the effect,” he said. But without strength across a broad enough collection of stocks, the indexes eventually feel the pain.

Then there have been central banks, which have used monetary policy in a bid to maintain growth and accommodate the markets. “There’s a lot of easy money out there,” said Carter Henderson, portfolio specialist and director of institutional development at Fort Pitt Capital Group. “It kind of kept markets in a delicate balance. But [disease] developments over the weekend opened the eyes of investors.”

Specifically, the increase of outbreaks in South Korea and Italy. Those spots are likely to be a far better predictor of what could happen in the U.S. than China is, according to some public health experts.

The big question at the moment is how much worse could things get in the short term. The answer, experts say, is “plenty.”

“You’ve got the Coronavirus and surge of Bernie Sanders and they’re feeding off each other,” observes William Zox, chief investment officer for fixed income at Diamond Hill Capital Management. “Regardless of what you think about the risks of the coronavirus, it looks like it could have enough of an effect on the economy, both in terms of significance and duration, that it could impact the election.” That, in turn, could cause further worry and downward pressure on stocks.

Victor Carlström, chairman of investment firm Vinacossa Enterprises, thinks U.S. investors are vastly underestimating the severity of the disease and its impacts. His company has offices in the U.S., Singapore, Cyprus, and Sweden and he travels heavily.

“I just got off the phone with a major fund manager in Singapore, and they are in a panic mode,” Carlström said. “All stores and malls are empty, and a lot of people are staying home, presumably because of the virus threat.” He’s also worried about signs that economic activity in Europe has slowed significantly.

“The only place where people act normal is in the U.S.,” Carlström said. First quarter earnings will be a “big shock because there’s no consuming in the rest of the world.”

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