Closing Bell: Delta Cancels Hundreds of Flights; U.S. Stocks Slip

U.S. stocks retreated from records as a selloff in health care overshadowed gains in energy. Crude oil was the winner of the day, rocketing higher on hopes of a production freeze deal between OPEC members. Crude closed at its best in two weeks. The energy sector was the best performer on markets Monday. Major oilers including Exxon Mobil (XOM) - Get Report , Chevron (CVX) - Get Report and ConocoPhillips (COP) - Get Report were each higher. Sotheby's (BID) - Get Report shot upwards after revenue fell far less than anticipated. Weaker sales were expected given lower agency commissions and a softer art market over the quarter.  Delta Airlines (DAL) - Get Report said 450 flights had been cancelled as of mid-afternoon after a technical snafu this morning caused its systems to go dark. The airline warned further delays and cancellations were a possibility.