the following is a summary of stock-based performance award and restricted stock award activity . stock-based performance awards weighted average grant date fair value restricted awards weighted average grant date fair value .
as of december 31 , 2007 , how much unrecognized compensation cost related to restricted stock awards is expected to be recognized in 1 year , in millions?
( a ) additional shares were issued in 2006 and 2007 because the performance targets were exceeded for the 36-month performance periods related to the 2003 and 2004 grants . during 2007 , 2006 and 2005 the weighted average grant date fair value of restricted stock awards was $ 54.97 , $ 40.45 and $ 27.21 . the vesting date fair value of stock-based performance awards which vested during 2007 , 2006 and 2005 was $ 38 million , $ 21 million and $ 5 million . the vesting date fair value of restricted stock awards which vested during 2007 , 2006 and 2005 was $ 29 million , $ 32 million and $ 13 million . as of december 31 , 2007 , there was $ 37 million of unrecognized compensation cost related to restricted stock awards which is expected to be recognized over a weighted average period of 1.4 year . 25 . stockholders 2019 equity common stock 2013 on april 25 , 2007 , marathon 2019s stockholders approved an increase in the number of authorized shares of common stock from 550 million to 1.1 billion shares , and the company 2019s board of directors subsequently declared a two-for-one split of the company 2019s common stock . the stock split was effected in the form of a stock dividend distributed on june 18 , 2007 , to stockholders of record at the close of business on may 23 , 2007 . stockholders received one additional share of marathon oil corporation common stock for each share of common stock held as of the close of business on the record date . in addition , shares of common stock issued or issuable for stock-based awards under marathon 2019s incentive compensation plans were proportionately increased in accordance with the terms of the plans . common stock and per share ( except par value ) information for all periods presented has been restated in the consolidated financial statements and notes to reflect the stock split . during 2007 , 2006 and 2005 , marathon had the following common stock issuances in addition to shares issued for employee stock-based awards : 2022 on october 18 , 2007 , in connection with the acquisition of western discussed in note 6 , marathon distributed 29 million shares of its common stock valued at $ 55.70 per share to western 2019s shareholders . 2022 on june 30 , 2005 , in connection with the acquisition of ashland 2019s minority interest in mpc discussed in note 6 , marathon distributed 35 million shares of its common stock valued at $ 27.23 per share to ashland 2019s shareholders . marathon 2019s board of directors has authorized the repurchase of up to $ 5 billion of common stock . purchases under the program may be in either open market transactions , including block purchases , or in privately negotiated transactions . the company will use cash on hand , cash generated from operations , proceeds from potential asset sales or cash from available borrowings to acquire shares . this program may be changed based upon the company 2019s financial condition or changes in market conditions and is subject to termination prior to completion . the repurchase program does not include specific price targets or timetables . as of december 31 , 2007 , the company had acquired 58 million common shares at a cost of $ 2.520 billion under the program , including 16 million common shares acquired during 2007 at a cost of $ 822 million and 42 million common shares acquired during 2006 at a cost of $ 1.698 billion. .