Shares on both sides of the Atlantic rose overnight as investors awaited the outcome of a British referendum about the UK's membership in the European Union, as recent surveys suggested more voters favoured the "Remain" option.
Polls will close at 10pm London time, and the first results are expected at about midnight.
There are no exit polls. However, YouGov, a pollster which successfully predicted the outcome of the 2014 Scottish independence referendum, will publish a poll of how people have voted shortly after polling stations close, according to Reuters.
Wall Street advanced. In 3.05pm New York trading, the Dow Jones Industrial Average climbed 0.95 percent, while the Nasdaq Composite Index rallied 1.18 percent. In 2.50pm trading, the Standard & Poor's 500 Index rose 0.99 percent.
"Regardless of the outcome in the UK, we will see a relief rally in the US today and tomorrow," Mohannad Aama, managing director, Beam Capital Management in New York, told Reuters. "I think we'll continue to go up tomorrow even if a 'Leave' vote prevails because there's a lot of money in the sidelines ... and that will be routed to safer havens and that includes US stocks."
The Dow moved higher, led by gains in shares of Goldman Sachs and those of Visa, recently up 2.8 percent and 2.1 percent respectively.