With a market cap of nearly $500 billion, Mastercard (MA 1.15%) is a true corporate giant. Indeed, it ranks as the 16th-largest American company by market cap, ahead of other financial behemoths like Bank of America, Wells Fargo, American Express, and Morgan Stanley.But why? And perhaps more importantly, will Mastercard retain its place in the years to come? Let's find out. Mastercard's greatest asset is its business modelLike its chief rival Visa, Mastercard has a business model based on payment processing ...