This excerpt taken from the C 8-K filed Jan 15, 2008.
DESCRIPTION OF THE CONVERTIBLE PREFERRED STOCK
The Convertible Preferred Stock will be issued pursuant to the terms of a Certificate of Designation that amends the Restated Certificate of Incorporation of Citigroup Inc. The terms of the Convertible Preferred Stock will include those stated in the Certificate of Designation, copies of which will be made available to prospective investors. The following summary of the material terms and provisions of the Convertible Preferred Stock is not intended to be complete and is qualified by the Certificate of Designation. If any specific information regarding the Convertible Preferred Stock in this description is inconsistent with the terms of the Convertible Preferred Stock described in the Certificate of Designation, you should rely on the information contained in the Certificate of Designation.