US stocks extended a rally for a third day on Tuesday as sharp gains in oil prices lifted energy shares and a rise in the euro currency pointed to a less risk-averse environment.

A raft of weak data has raised expectations that the European Central Bank will cut interest rates to a record low on Thursday, when US traders return from the July 4 holiday, in a move that could drive stock markets higher.

Eric Kuby, chief investment officer, North Star Investment Management in Chicago, said that last week's European summit, which sparked the rally with measures to ease the bloc's crisis, has raised expectations that policymakers globally are waking up to the need to support financial markets and the economy.

“We have been in rally mode,” he said. “It's hard to buy into the actual economic numbers as really moving the market as they seem to be so dwarfed by the this whole global liquidity situation.”

Brent crude oil topped $101 a barrel for the first time in three weeks as tension over Iran increased concerns about threats to supply and as investors bet on further policy action. The S&P's energy sector was the top gainer, up 1.8 percent.

The euro continued to rally in late morning in New York, climbing to a session peak in thin liquidity as investors positioned for the European Central Bank policy meeting.

Major automakers also posted stronger-than-expected sales gains in June. Shares of Ford Motor Co, General Motors Co and other big car manufacturers rose on the news.

The Dow Jones industrial average gained 63.76 points, or 0.50 percent, to 12,935.15. The Standard & Poor's 500 Index rose 7.86 points, or 0.58 percent, to 1,373.37. The Nasdaq Composite Index added 20.28 points, or 0.69 percent, to 2,971.51.

The S&P 500 has gained 3.3 percent over the last 3 sessions, its best such runs since December. The move has lifted the S&P 500 out of a recent trading range from 1,350-1,360, identified by analysts Brown Brothers Harriman.

Microsoft Corp shares were flat at $30.57 on Tuesday after the company admitted its purchase of aQuantive, its largest acquisition in the Internet sector, was effectively worthless and wiped out any profit for the last quarter.

The Commerce Department said new orders for manufactured goods rose 0.7 percent during May. Economists had forecast orders rising 0.2 percent.

Trading is expected to remain volatile on low volume as US stock markets close at 1 p.m. ET. (19:00 SA time) ahead of the Independence Day holiday on Wednesday. Volume is likely to start building up from early Thursday, ahead of Friday's non-farm payrolls data.

“Investors have to be prepped for one of two outcomes on Friday. Our baseline is at or below the consensus 90,000 figure in which case more stimulus is on the cards. The risk is a bigger number that leaves a 30-point air-pocket above the current market level,” said Andrew Wilkinson, chief economic strategist at Miller & Co in New York.

A US ISM manufacturing report on Monday, whose main index registered a contraction in the sector for the first time since July 2009, boosted speculation that the Federal Reserve will announce it will embark on a third round of asset purchases, known as 'QE3', perhaps as soon as the central bank's next policy meeting from July 31 to August 1.

The US Justice Department is probing Chesapeake Energy Corp and Encana Corp for possible collusion after a Reuters report showed that top executives of the two rivals plotted in 2010 to avoid bidding against each other in Michigan land deals, a source close to the probe said. Chesapeak shares were up 2.1 percent at $19.12.

US investment management firm BlackRock is buying Swiss Re's European private equity and infrastructure fund of funds franchise, it said on Tuesday. - Reuters