The Dow Jones Industrial Average plummeted more than 500 points this morning as U.S. investors reacted to Britain's decision to leave the European Union This is the biggest drop for the Dow in 10 months The Nasdaq dropped more than 176 points, while the Standard and Poor 500 slid more than 54.94 points after U.S. markets opened Friday for trading The Brexit vote stunned investors, pushing global markets and currencies to fall