In the following video, Motley Fool financial analysts David Hanson and Matt Koppenheffer discuss Citigroup (C -0.32%) and what makes it such a difficult business for investors to understand.

David tells us why Citigroup's two entities, Citicorp and Citi Holdings, are wildly disparate in their performances, as well as why Citigroup's exposure to the foreign exchange market further complicates forming an investment thesis on this stock. Matt then tells us what type of investor might thrive looking at a complex business model like this one, and which types of investors might be better served elsewhere.