S&P 500's 1.2% gain for May pushes year's advance over 2%.
Pre-holiday weekend trading volume was the second-lowest this year.
Oil rises to highest level since October last year.
New home sales in the US are at an eight-year high.
A slew of economic data in the coming days will be closely watched.
The Dow's fall all but erases the index’s gains for the year.
The Meeting Place of Intelligent Business