In August 2005, the company acquired Unocal Corporation (Unocal), an independent oil and gas exploration and production company. The aggregate purchase price of Unocal was $17,288. The final purchase-price allocation to the assets and liabilities acquired was completed as of June 30, 2006.

The following unaudited pro forma summary presents the results of operations as if the acquisition of Unocal had occurred at the beginning of 2005:

Year ended December 31
2005
Sales and other operating revenues $ 198,762
Net income 14,967
Net income per share of common stock
Basic $ 6.68
Diluted $ 6.64

The pro forma summary used estimates and assumptions based on information available at the time. Management believes the estimates and assumptions to be reasonable; however, actual results may have differed significantly from this pro forma financial information.