Company Reports 2011 First Quarter Net Loss to Common Stockholders of $205 Million, or $0.32 per Fully Diluted Common Share, on Revenue of $1.6 Billion; Company Reports Adjusted Net Income Available to Common Stockholders of $518 Million, or $0.75 per Fully Diluted Common Share, Adjusted Ebitda of $1.3 Billion and Operating Cash Flow of $1.4 Billion 2011 First Quarter Production Averages 3.107 Bcfe per Day, an Increase of 20% over 2010 First Quarter Production and 6% over 2010 Fourth Quarter Production; 2011 First Quarter Liquids Production Increases 56% Compared to the 2010 First Quarter and 9% Compared to the 2010 Fourth Quarter; 2011 First Quarter Liquids Production Accounts for 13% of Total Production and 23% of Realized Natural Gas and Oil Revenue Proved Reserves Total 15.6 Tcfe Following the Sale of 2.5 Tcfe of Proved Reserves; Company Adds New Net Proved Reserves of 1.3 Tcfe Through the Drillbit at a Drilling and Completion Cost of $1.25 per Mcfe Company's Leasehold Reaches 1.2 Million Net Acres in the Utica Shale Play in the Appalachian Basin and 1.1 Million Net Acres in the Mississippian Carbonate Play in Northern Oklahoma and Southern Kansas; JV Process is Expected to Commence for Each Play in the 2011 Second Half Company Highlights its Oilfield Service Vertical Integration Strategy and Estimates that its Oilfield Service Assets Are Worth Approximately $7.0 Billion