Trading in US shares was briefly suspended after sharp falls led to an automatic halt in the selling and buying of stocks.
Once trading resumed, the three major US stock indexes were down over 6 percent.
The move follows dramatic falls globally with shares facing the worst day since the 2008 financial crisis.
A row between Russia and Saudi Arabia saw oil prices plunge by 20 percent, hitting markets already reeling from fears of the impact of the coronavirus.
The day has been dubbed "Black Monday" by analysts who described the market reaction as "utter carnage".
Senior editor at Bloomberg, John Authers, speaks to Corin Dann.