X0202 4 2007-05-04 0 0001037676 ARCH COAL INC ACI 0001129715 MESSEY ROBERT J ONE CITYPLACE DRIVE ST. LOUIS MO 63141 0 1 0 0 Senior Vice President & CFO Common Stock 2007-05-04 4 M 0 19150 A 57238 D Performance Rights 2007-05-04 4 M 0 38300 D 2008-12-31 Common Stock 38300 38300 D The reporting person received 76,600 performance-contingent phantom shares on July 28, 2005. One-half of the performance contingent phantom shares vest if the average closing price of Arch Coal, Inc.'s common stock for a period of 20 consecutive trading days meets or exceeds $35.00, subject to the achievement of certain financial performance targets. Upon vesting of 38,300 performance contingent phantom shares on May 4, 2007, the reporting person received 19,150 shares of common stock and $703,763 in cash. Each performance-contingent phantom share represents a right to receive one share of common stock or the cash value thereof, unless otherwise deferred at the reporting person's election, pursuant to the Arch Coal, Inc. Executive Deferred Compensation Plan. The reporting person received 76,600 performance-contingent phantom shares on July 28, 2005. One-half of the performance-contingent phantom shares vest if the average closing price of Arch Coal's common stock for a period of 20 consecutive trading days meets or exceeds $35.00 and the other half of the performance shares vest if the average closing price of Arch Coal's common stock for a period of 20 consecutive trading days meets or exceeds $40.00, subject, in each case to the achievement of certain financial performance targets. On May 4, 2007, 38,300 performance-contingent phantom shares vested. /s/ Gregory A. Billhartz, Attorney-in-Fact 2007-05-08