In June 2006 , Banco Santander Central Hispano purchased almost 20 % of Sovereign Bank . They also acquired the option to buy Sovereign Bank for $ 40 per share in the middle of 2008 . In June 2006 , Banco Santander Central Hispano purchased almost 20 % of Sovereign Bank and acquired the option to buy the bank for $ 40 per share for one year beginning in the middle of 2008 .