STOCKS GET CRUSHED: Here's what you need to know

Stocks tumbled from their strongest levels of the day as false rumors swirled that Gary Cohn, President Donald Trump's top economic adviser, was resigning. They lost more ground after a van plowed into a crowd in Barcelona, Spain, in what authorities said was a terrorist attack. 
Here's the scoreboard: 
Dow: 21,750.73, -274.14, (-1.24%)
S&P 500: 2,430.01, -38.10, (-1.54%)
Nasdaq: 6,221.91, -123.19, (-1.94%)
Walmart on Thursday reported second-quarter earnin