The S&P 500, a stock index that consists of 500 of the United States’ largest companies, fell by 1.83 percent to close at 2,020.58, its biggest decline since October 9, 2013.
The S&P 500 energy index fell by 4 percent, a daily percentage drop it has not seen since late November. In addition, the US crude oil prices fell below $50 a barrel for the first time since 2009.
Oil prices have been plummeting since the summer of 2014, falling from more than $110 per barrel to some $50 per barrel due to oversupply in the market.
Earlier on Monday, White House spokesperson Josh Earnest stated that falling oil and gas prices were beneficial for the US economy and middle class families.