I have to respectfully disagree, mainly because Amex is a company I cover for a living (research analyst). The common misperception is Amex doesn’t make much on interest charges given their higher quality portfolio; yes and no. While Amex boast higher asset quality than their fellow peers, they have had to expand their customer base given earnings pressure and margin compression, and with that, interest fees. Small business loans, and believe it or not, personal loans, do account for a meaningful stream of revenue, but you are correct in that in its unique capacity as both a payment processor and its own bank, a sizable portion is attributed to interchange fees, but that has since been diversified.
I need to stop before I put everyone to sleep...