Updated from 7:42 a.m. EDTCitigroup ( C) said Thursday it plans to file a proxy statement with the Securities and Exchange Commission for approval to increase its number of authorized common shares and to amend its charter to allow for a reverse stock split of its common stock. The bank also filed with the SEC for its proposed offer to issue common stock in exchange for publicly held convertible and non-convertible preferred and trust preferred securities. In a statement, Citigroup said it anticipates launching the public exchange offer in early April. Last month, Citigroup announced that it would enter into an agreement with the U.S. Treasury to convert its preferred shares into common shares in order to build the company's tangible common equity. The agreement is expected to increase the bank's tangible common equity ratio to as much as $81 billion from $29.7 billion at the end of the fourth quarter. Citigroup is seeking to exchange about $27.5 billion in preferred shares with a commitment from the U.S. Treasury to convert up to an additional $25 billion of its preferred securities for common stock.