vichie81/iStock(NEW YORK) -- Trading was temporarily halted Wednesday after U.S. financial markets plunged amid another day of volatility over the novel coronavirus crisis.

The S&P 500 dipped below the 7% threshold just before 1 p.m., triggering a 15-minute halt to trading on Wall Street.

By midday, the Dow was down more than 1,700 points, or 8%. The S&P 500 fell 7% and the Nasdaq dropped more than 6%. Oil hits lowest level in more than 18 years.

The Dow briefly dipped below where it trading when President Donald Trump took office.

Among the worst performers Wednesday was Boeing, with shares tumbling more than 18%. Marriott dropped by approximately 30% after reports of coming furloughs and layoffs.

It has already been a roller-coaster week for equity markets as the novel coronavirus crisis continues to sow massive uncertainty on the global economy. On Monday, the Dow suffered its worst day since the "Black Monday" crash of 1987, dropping nearly 3,000 points or 12.94%. On Tuesday, however, the index rebounded more than 1,000 points, or over 5%, as Trump administration officials touted a major stimulus package.

"When there is an event that leads to selling, such as coronavirus uncertainty, it catapults into more selling," David Bahnsen, the chief investment officer of the Bahnsen Group, said in a commentary Wednesday. "This creates downward pressure on almost all assets, including good assets."

He continued, "All of the panic and margin selling eventually runs its course. It's an incredibly bad time for people who don't have to sell to be selling -- because they are selling into an avalanche."

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