Now it probably means someone has tripped over the power cord at one of the big algo futures traders (think drunk partner at RSJ),
From Bespoke Investment Group:
As shown in the chart below, for the fourth time in as many days, the S&P 500 closed today down more than 1% from its intraday high. Just a week after one of the broadest equity market rallies in decades, sentiment has shifted on a dime, and investors are taking the term 'sell into rallies' to a new level....MORE