Visa and MasterCard are far-and-away the leaders in the credit card space when it comes to global payment volume. Although it has a different business model which includes extending credit to customers, American Express could present a substantial threat if it wanted to. In this segment of The Motley Fool's everything-financials show, Where the Money Is, analysts Matt Koppenheffer and David Hanson ponder a scenario of American Express changing its business to directly attack Visa and MasterCard.
