By CATHERINE THORBECKE, ABC News

(NEW YORK) — The Dow Jones Industrial Average slid by more than 300 points, or 1.2%, when U.S. markets opened Friday following news that President Donald Trump has tested positive for COVID-19.

The S&P 500 dropped by approximately 1% and the Nasdaq was down 1.35% as investors awoke to the new uncertainty.

Global financial markets also reeled on the news. Germany’s DAX shed 1.3% Friday and Britain’s FTSE index was down by about 1%. France’s CAC 40 Index lost nearly 1.2%.

In Asia, Japan’s Nikkei 225 index was off 0.7%.

White House physician Dr. Sean Conley said early Friday that the president and first lady Melania Trump, who also tested positive for the virus, were “both well at this time” and plan to remain in the White House as they recover.

Mark Hamrick, Bankrate’s senior economic analyst, said news of the president and first lady testing positive for COVID-19 “marks the addition of further uncertainty when it was already abundant, typically toxic for financial markets.”

“Aside from the personal implications for the first family, this and any related developments will likely be key drivers for stock investors in the near term,” he added. “Longer term and outside the news cycle, the typical drivers will remain most relevant, including earnings, dividends and interest rates. As is always the case, long-term investors need to try to look through the near-term fog.”

The stock market is at “some risk of heightened volatility in the coming days and weeks” because of the upcoming election, Hamrick noted, but the president’s diagnosis “may exacerbate that risk amid no shortage of other sources of uncertainty and volatility.”

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