From Bloomberg:

Stocks opened sharply higher Monday on Wall Street, building on a massive rally that began abroad, as investors reacted to fresh polls that show the "Remain" camp is gaining momentum in the "Brexit" vote, a shift in sentiment that boosts odds and raised hopes that Britain will stay in theEuropean Union.

The Dow Jones industrial average was up 240 points, or 1.4%, at the open. The broader Standard & Poor's 500 stock index was up 1.3% and the Nasdaq composite rose 1.3%.

The new polls have boosted investment sentiment, which is shifting away from the risk aversion that marked last week's trading, when investors fearing a UK vote this Thursday to leave the EU sold assets that would be hurt most by the uncertainty and economic downside of a Brexit, such as stocks, commodities, and the British pound and banks.