People pass the New York Stock Exchange, Friday, June 24, 2016. Britain voted to leave the European Union after a bitterly divisive referendum campaign, toppling the prime minister Friday, sending global markets plunging and shattering the stability of a project in continental unity designed half a century ago to prevent World War III. (AP Photo/Richard Drew)

Dow closes down 611 points

The Dow Jones industrial average dropped 611 points, or 3.4 percent, to 17,399 in heavy trading Friday.