Wells Fargo & Co. (WFC) Friday agreed to buy all of Wachovia Corp. (WB) for about $15 billion in stock, however, Citigroup Inc. (C), which had already agreed to buy Wachovia’s banking operations, immediately issued a protest that could jeopardize the deal. “Citi has substantial legal rights regarding Wachovia and this transaction,” Citi said in a statement. “Wachovia’s agreement to a transaction with Wells Fargo is in clear breach of an exclusivity agreement between Citi and Wachovia.” Wells Fargo’s $15 billion, or $7 a share, all-in bid easily trumps Citigroup’s $2.16 billion, or $1 per share, offer for Wachovia’s deposits, loan portfolio, and retail banking branches. The Citigroup offer did not include Wachovia’s A.G. Edwards brokerage unit or Evergreen mutual fund family. “It provides superior value compared to the previous offer to acquire ...