They're not settled instantly, but broadly, this is one of the reasons the credit card networks are a massive accomplishment; they settle deterministically enou

They're not settled instantly, but broadly, this is one of the reasons the credit card networks are a massive accomplishment; they settle deterministically enough that a commanding majority of financial institutions will trust the networks sufficiently to transact with them. Yes, this is accomplished by absolutely massive amounts of (mostly offsetting) debts carried between various parties every day of the last several decades. I should probably write more about this subject at some point, but the GP is of course correct; the credit card networks (except for Amex) generally do not put up money at any point. Each entity in a chain about 5 links long makes simultaneous and very quick agreements about offsetting transactions between themselves, with probabilistic assurance of eventual settlement to the business being "very, very quick" and physical settlement happening in a few days to about a month later. Typically an important step is the issuing bank settling with an intermediary (not the network) who will settle with the merchant bank or payment processor who will settle with the business.