DOW JONES NEWSWIRES Standard & Poor's said it will move independent natural gas and oil exploration company WPX Energy Inc. (WPX) into its S&P 500 index, replacing technology-management software maker Compuware Corp. (CPWR). Compuware will drop down to S&P's MidCap 400 index, replacing Exterran Holdings Inc. (EXH), a provider of oil and gas equipment. In turn, Exterran will take the place of Skyline Corp. (SKY) in the S&P SmallCap 600 index. The changes will take place after the close of trading on Dec. 30. Williams Cos. Inc. (WMB), which will remain a member of the S&P 500, is expected to spin off WPX Energy on Dec. 31. Compuware's market capitalization is below $1.9 billion and no longer warrants a spot in the top index, S&P said. Exterran's market capitalization is below $600 million and is more representative of the small cap market space. Skyline is ranked in the 600th spot in the SmallCap index. -By Nathalie Tadena, Dow Jones Newswires; 212-416-3287; nathalie.tadena@dowjones.com
