Wall Street bull Edward Yardeni isn't sure how much longer investors will shrug off coronavirus fears.
He sees the outbreak as the most critical risk to the record stock market rally.
"That's all I really see," the Yardeni Research president told CNBC's "Trading Nation" on Friday. "The longer that this virus threat continues to weigh on the global economy, the more it poses a risk for at least a correction in the stock market."
A correction is a decline of at least 10% from recent highs.
Yardeni, who spent decades on Wall Street running investment strategy for firms including Prudential and Deutsche Bank, came into the year on pullback watch. Even though he's a long-term bull, Yardeni believes stretched market valuations have been increasing correction risks for months.
According to Yardeni, coronavirus fears could emerge as the catalyst that puts the record rally on pause.
"The markets have done remarkably well in the face of headline news that's still unsettling like cruise ships being quarantined and China basically being completely quarantined because of cancellations of flights," he said. "That's got to be disruptive for supply chains."
"The global economy was actually starting to show signs of improving before the virus became headline," said Yardeni.
If the coronavirus outbreak contributes to the market's next serious leg lower, he believes U.S. stocks will rebound quickly.
"Interest rates are so extraordinarily low," he noted. "The central banks have basically provided no interesting reasons to buy in the fixed-income markets and lots of reasons to buy in the stock market."
But that doesn't mean Yardeni is recommending an all-in approach to stocks.
"If I've got some spare cash, I'd like to just keep it as dry powder until I get a little bit more clarity on this coronavirus," Yardeni said.