Shares of Keurig Green Mountain Inc (NASDAQ:GMCR) are higher this morning after the company was invited to join the S&P500. Effective after the close of trading on March 21st, Keurig Green Mountain will replace WPX Energy Inc (NYSE:WPX) in the S&P500. Keurig Green Mountain has been riding high lately with the Coca-Cola Company (NYSE:KO) deal.WPX Engery produces and explores oil and natural gas. WPX’s new home will be the S&P MidCap 400.