Partnership Reports 2010 Fourth Quarter Net Income of $90 Million and Adjusted Ebitda of $116 Million Partnership Completes Acquisition of Springridge Gathering System from Chesapeake Energy Corporation Partnership Reaffirms 2011 Outlook and Capital Program

Company Reports 2010 Fourth Quarter Net Income to Common Stockholders of $180 Million, or $0.28 per Fully Diluted Common Share, on Revenue of $2.0 Billion; Company Reports Adjusted Net Income Available to Common Stockholders of $478 Million, or $0.70 per Fully Diluted Common Share, Adjusted Ebitda of $1.3 Billion and Operating Cash Flow of $1.2 Billion 2010 Full Year Net Income to Common Stockholders Was $1.7 Billion, or $2.51 per Fully Diluted Common Share, on Revenue of $9.4 Billion; 2010 Full Year Adjusted Net Income Available to Common Stockholders Was $2.0 Billion, or $2.95 per Fully Diluted Common Share, 2010 Full Year Adjusted Ebitda and Operating Cash Flow Were $5.1 Billion and $4.5 Billion, Respectively 2010 Full Year Production Averages 2.836 Bcfe per Day, an Increase of 14% Year over Year; 2010 Year-End Proved Reserves Reach 17.1 Tcfe; Company Adds Proved Reserves of 5.1 Tcfe through the Drillbit at a 2010 Full Year Drilling and Completion Cost of $1.07 per Mcfe