NEW YORK (CBSNEWS.COM) – U.S. stocks plunged so quickly Monday that trading was halted as frightened investors fled the markets amid growing economic uncertainty over the spreading coronavirus. Oil markets also collapsed after Saudi Arabia said it plans to slash prices, escalating a battle with Russia just as the coronavirus’s impact is reducing demand for oil.

Traders work during the opening bell at the New York Stock Exchange (NYSE) on March 5, 2020 at Wall Street in New York City. (credit: Johannes EiseleI/AFP via Getty Images)

Trading was halted shortly after the markets opened at 8:30 a.m. CST, triggered by a 7% plunge in the S&P 500 index. The S&P 500 has three “circuit breakers” that kick in when stocks decline by either 7%, 13% or 20% in a trading session.

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