redecard ipo in 2007 , citigroup ( a 31.9% ( 31.9 % ) shareholder in redecard s.a. , the only merchant acquiring company for mastercard in brazil ) sold approximately 48.8 million redecard shares in connection with redecard 2019s initial public offering in brazil . following the sale of these shares , citigroup retained approximately 23.9% ( 23.9 % ) ownership in redecard