What do Visa and Mastercard do? An intro to card networks
TL;DR
Visa and Mastercard don't issue cards, lend money or sign up merchants. They route authorization messages between banks and settle the money between them. They also set the fees and write the rules. On a typical $100 US credit purchase, the network takes about $0.15. The issuer, the cardholder's bank, keeps $2.
The article
- Card networks connect two sides. The issuing side is the cardholder and their bank, the issuer. The acquiring side is the merchant and its acquirer or a processor such as Stripe. Issuing, acquiring, card printing and point-of-sale hardware all belong to other companies.
- The first job is a telecom network. Visa runs hardened data centers and forwards authorizations from merchant to issuer. The card number works like an IP address. Its first 6 to 8 digits identify the issuer. Clearing later finalizes the amount, for example after a tip is added.
- The second job is moving money. Visa nets each participant's debits and credits once a day. It also converts currencies across borders. Its 2024 filing reports a peak daily settlement exposure of $137.4 billion. Visa holds $11.2 billion in case a bank fails to pay.
- On a $100 US credit transaction the merchant pays 2.5%. The processor keeps $0.35. Visa gets $0.15 as an assessment fee. The issuer keeps $2.00 of interchange, which the network sets. That split is why issuers fund lavish rewards. It is also why the EU's 0.3% interchange cap leaves Europe with few rewards cards.
- The networks also enforce a 923-page rulebook. They run the dispute process too. Issuer and acquirer trade evidence until one side gives up. If neither does, Visa decides the case for a $600 fee that the loser pays. So most disputes end with someone simply refunding.
- The author calls this arbitration efficient but not fair. The system, the author says, is built to encourage transactions more than to stop fraud. That leaves room for 'friendly fraud' by cardholders.
Why it matters
A good primer for developers or founders who touch payments and keep mixing up issuers, acquirers, processors and networks. The original has the flow diagrams, the 10-K excerpts on settlement risk and footnotes on BINs running out of numbers, surcharging and voice authorizations.
The discussion
A long, heated thread that mostly skipped the article's mechanics and argued about whether the US card system is a racket. The biggest subthreads compared debit and credit fraud protection, asked who really pays for rewards, and fought over whether cash is cheaper for merchants. Europeans and Brazilians pointed to fee caps, Pix and Wero as proof that cheaper systems exist.
Debit vs credit when fraud hits
The top thread started with someone wishing for a no-fee card, and the reply 'that's a debit card' set off the longest argument. Most US commenters said credit is safer, since debit fraud empties your checking account until the bank finishes investigating. lxgr pushed back that Regulation E and network rules give debit nearly the same protection, and some had banks refund debit fraud within a day. UK commenters said their law forces fast refunds either way.
In the US, a charge on your bank card results in at least a hold on your bank account - money you can't spend on anything else until the hold is lifted. Worst-case, there can be significant fees associated with this (overdraft, declined payments, etc.).
Debit card liability is also largely mandated to be $0 under card scheme rules.
Who pays for the rewards
Many argued that merchants bake fees into prices, so cash and debit users subsidize rewards cardholders. They cited the recent HBS piece calling it a transfer from poor to rich. Others rejected the accounting, saying store revenue isn't fixed and perks for big spenders resemble a volume discount. Nearly everyone, critics included, admitted to playing the points game anyway, since opting out alone changes nothing.
Prices reflect the credit card merchant fees, even if there's no separate surcharge. People pay higher prices and anyone who doesn't use a credit card to recoup some in "rewards" is effectively getting taxed.
The only way to break the cycle of self-reinforcing incentives would be swift regulatory action. Absent that, playing the game is the rational move at the individual level for both merchants and consumers.
Is cash actually cheaper for merchants
One camp listed the hidden costs of cash: counting, bank runs, safes, employee theft and robbery. A Swedish commenter credited cashless payments with a collapse in armored-car and bank robberies. A small business owner answered with numbers, a $400 cash counter against $400 a month in Square fees. Others noted that cash discounts often mean the merchant is skipping VAT or sales tax.
I bought a cheap cash and coin counter for about $400 on Amazon, which means it takes me about 2m to count whenever I need to balance the register.
For reference, with my POS I pay about $400 per MONTH in card fees (square).
In 2009 Sweden had 58 armored car robberies, in 2018 there were 1. This used to be a big concern in Sweden, now it's basically a nonissue.
Cartel or hard-won network
Critics called Visa and Mastercard rent-seekers whose fees far exceed their running costs, citing operating margins of 67% and 58%. Defenders said a global bank-to-bank network is hard to build, and that anyone who built a better one would win. The reply was that network effects stop the better system from winning. lxgr noted that even if the network's own cut is small, it sets interchange and enforced 'honor all cards' rules that kept fees high.
These networks would be usurped if someone could actually come up with a better system. The economy insists upon it constantly.
But they set the interchange rates and disallow (or at least have until recently, in the US) merchants to discriminate against cards based on rate or type via their “honor all cards” rules.
Public alternatives: Pix, UPI, Wero, FedNow
Commenters held up Brazil's Pix, India's UPI, Germany's Girocard and Europe's Wero as cheaper rails, and pointed out the US government's investigation of Pix. toomuchtodo argued FedNow already gives the US the base layer and cited Walmart's pay-by-bank trial. lxgr answered that a payment rail is not a retail scheme. Banks, rewards-loving cardholders and networks all have reasons to keep cards on top.
FedNow is a payments rail, which is a long shot away from being a full retail payments scheme. The latter needs a disputes story, customer knowledge, merchant acceptance…
Walmart is currently trialing it to save $3B-$7B a year in interchange fees. No crypto, just XML messages through a mainframe at the Federal Reserve with a 20 second SLA.
Consensus
US interchange is far higher than it needs to be. Issuers get most of it, and individuals can't escape it by paying differently. Only regulation like the EU cap or a public rail changes the incentives. Credit cards' chargeback rights are worth something real.
Dissent
A minority defended the networks as efficient trust machines that let strangers in different countries trade safely for a small cut. They argued merchants accept cards because cards bring sales and cut cash losses, not because they are forced to.