Banco Bradesco S.A. (BOVESPA:BBDC4) and Banco do Brasil S.A. (BOVESPA:BBAS3) are in talks to buy Citigroup Inc.'s (NYSE:C) stake in a credit card processing joint venture with Elavon Inc., a source with knowledge of the negotiations said. The acquisition could be closed next month by Banco Bradesco and Banco do Brasil's holding company Elo Participações S.A., the source said, asking not to be named because the discussions are confidential. Representatives for Banco Bradesco, Banco do Brasil and Citigroup declined to comment on the talks.