Chesapeake Energy (CHK)

UNAUDITED PRO FORMA CONDENSED COMBINED FINANCIAL INFORMATION

On November 14, 2005, pursuant to a purchase agreement dated September 30, 2005, Chesapeake Energy Corporation (“Chesapeake”) completed its acquisition of Columbia Energy Resources, LLC and its related subsidiaries including Columbia Natural Resources, LLC (“Columbia”), for $2.2 billion in cash. Through this transaction, we acquired properties and assets principally located in the Appalachian Basin in West Virginia, Kentucky, Ohio, Pennsylvania and New York. The acquisition was funded using available cash on hand, a private offering of $500 million of 6.875% Senior Notes due 2020, a private offering of $690 million of 2.75% Contingent Convertible Senior Notes due 2035, a private offering of 5,750,000 shares of 5.00% cumulative convertible preferred stock having a liquidation preference of $100 per share and a public offering of 23 million shares of common stock at $31.46 per share.

The following unaudited pro forma condensed combined statement of operations is derived from the historical financial statements of Chesapeake Energy Corporation and Columbia Energy Resources, LLC. The pro forma combined statement of operations for the year ended December 31, 2005 reflects the Columbia acquisition as if the acquisition occurred on January 1, 2005. The unaudited pro forma condensed combined statement of operations should be read in conjunction with the notes thereto and the historical financial statements, including the notes thereto, of Chesapeake included in its Annual Report on Form 10-K for the year ended December 31, 2005 and of Columbia included in Chesapeake’s Current Report on Form 8-K dated November 1, 2005.

The pro forma information below is presented for illustrative purposes only and is based on estimates and assumptions deemed appropriate by Chesapeake. The pro forma information should not be relied upon as an indication of the operating results that Chesapeake would have achieved if the acquisition had occurred at the beginning of 2005, or of future results that Chesapeake will achieve after the Columbia acquisition.

The Columbia acquisition was accounted for using the purchase method of accounting. The purchase cost was allocated to the identifiable Columbia tangible and intangible assets and liabilities based on their respective fair values, including derivatives whose valuation was dependent upon gas prices at the time of closing.