.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