U.S. stocks open sharply higher as Brexit vote begins

U.S. stocks opened sharply higher Thursday as investors eagerly awaited the outcome of Britain's Brexit referendum that started early in the morning.

Voters have been going to polling stations Thursday to cast their votes to decide whether Britain will stay in or leave the European Union, as downpours hit London and southeast England.

The ballot counting will start as soon as the polls close at 10 p.m. local time (2100 GMT). A total of 382 counting areas will be set up, with 380 located in England, Wales and Scotland, one in Northern Ireland and one in Gibraltar.

The outcome is expected to be officially declared at the Manchester Town Hall in the early hours of Friday.

According to six main opinion polls from June 18 to 22, the "Leave" camp was tied with the "Remain" camp.

On the U.S. economic front, in the week ending June 18, the advance figure for seasonally adjusted initial claims decreased 18,000 from the previous week's unrevised level to 259,000, below market consensus, the Labor Department reported Thursday.

Shortly after the opening bell, the Dow Jones Industrial Average jumped 164.23 points, or 0.92 percent, to 17,945.06. The S&P 500 added 16.89 points, or 0.81 percent, to 2,102.34. The Nasdaq Composite Index gained 35.84 points, or 0.74 percent, to 4,869.16.

On Wednesday, U.S. stocks reversed early gains to end lower, as Wall Street assessed U.S. Federal Reserve Chair Janet Yellen's comments ahead of the Brexit vote. Endi