Chesapeake Midstream Partners, an L.P. formed by Chesapeake Energy and GIP to operate natural gas gathering systems, raised $446 million by offering 21.25 million shares at $21.00, the high end of the $19-$21 range. The company plans to list on the NYSE under the symbol "CHKM". UBS Investment Bank, Citi, and Morgan Stanley were the lead underwriters on the IPO.