[skilbjo]

Whilst interchange is indeed the largest part of processing costs, there are still assessments (0.13%) and brand fees (FANF, cross border fees (1.25% for Visa), etc) that increase the cost of processing over interchange.

Square can only hope to make a decent margin on its 2.75% pricing by 1. seeing a preferred distribution mix on card types (such as, high debit card usage; less Amex; less expensive rewards cards; high cards qualifying at card present rates & no downgrades) and/or 2. special interchange discounts with the networks based on growth initiatives and/or fraud tools.

If they can't generate enough $$ from processing revenue, they'll need to use card processing as a loss leader for other services (loans, analytics, marketing)...