This paper explains why payment card companies charge consumers and merchants fees which are proportional to the transaction values instead of charging a fixed per-transaction fee. Our theory shows that, even in the absence of any cost considerations, card companies earn much higher profit when...

This paper explains why payment card networks charge fees that are proportional to the transaction values instead of charging fixed per-transaction fees. We show that, when card networks and merchants both have market power, card networks earn higher profits by charging proportional fees. It is...