On June 3, 2026, Mastercard said it would let issuers and acquirers settle in regulated stablecoins, starting with Circle's USDC and including Paxos-issued tokens and Ripple's RLUSD. By April 2026, Visa's stablecoin settlement reached a $7 billion annualized run rate across nine blockchains. Stablecoins have moved from the edges of crypto trading into payments infrastructure, and that shift now shows up in payments PM interviews. This guide covers what a stablecoin is, where it helps in payments, the regulation you need to know, and how interviewers test the topic.
What a stablecoin is
A stablecoin is a digital token pegged to a unit of fiat money, almost always the US dollar, and backed by reserves under the issuer's control. It moves on a blockchain, so it can transfer between wallets at any hour, including weekends, without waiting on a bank-rail window. The two largest are Circle's USDC and Tether's USDT. PayPal issues PYUSD, and Ripple issues RLUSD. For a payments PM, the useful mental model is a dollar balance that settles on a public network rather than through the card networks or the ACH system.
Why payments teams care
The appeal is settlement. A wire clears only during banking hours, and an international payment can take days and pass through several correspondent banks, each taking a fee. A stablecoin transfer settles in minutes, around the clock, for a fee the network sets rather than the correspondent banks. That matters most for cross-border payouts, treasury movement between entities, and any flow that today waits on a wire window. Mastercard framed its own move around intraday and weekend settlement, which is the same idea applied to card settlement.
In interviews, the point to make is that a stablecoin is only one option in a set of rails. It competes with cards, ACH, wires, and real-time rails like RTP and FedNow. A complete answer treats it as a tool with a specific fit, not a wholesale replacement for every rail.
The regulation you have to know
Payments and regulation travel together, and stablecoins are now governed by a federal law. The GENIUS Act, enacted in July 2025, is the federal law that now governs payment stablecoins. It created a framework for payment stablecoins and generally bars anyone other than a permitted payment stablecoin issuer from issuing one to US customers. A permitted issuer is either a bank subsidiary or a nonbank fintech approved for the new federal license. Issuers have to back tokens with high-quality reserves and meet anti-money-laundering and sanctions obligations under the Bank Secrecy Act.
The rules are still a work in progress. The OCC issued its proposed rulemaking in February 2026, comments were due by May 1, and the FDIC followed with its own proposal. By mid-2026, those agencies, the Federal Reserve, and the Treasury had not yet issued final rules. A payments PM does not need to recite the statute, but should know who is allowed to issue, that reserves and redemption matter, and that KYC and sanctions screening attach to the flow.
What a payments PM owns here
If a team adds stablecoin payments, the PM owns a set of decisions that go beyond the happy path. Custody is the first: who holds the keys, and is it the company, a regulated custodian, or the user. Chain selection is the next, because fees, speed, and supported tokens differ across networks. On-ramps and off-ramps are where most user friction lives, since someone has to convert dollars to the token and back, and that step carries fees, identity checks, and a timing constraint. Treasury and reconciliation come after, because finance still needs every movement matched to a ledger entry and a report. Compliance runs through all of it: identity verification, sanctions screening, and, for cross-border flows, travel-rule data on sender and recipient.
How interviewers probe it
Expect open design and judgment questions. "Design a stablecoin payout product for cross-border contractors." "When would you settle a payment in USDC instead of sending a wire?" "How would you handle the on-ramp and off-ramp, and who absorbs the fees and FX?" A complete answer starts with the rail comparison, names the case where the stablecoin clearly wins, such as a weekend cross-border payout, and then states the constraints: custody, the GENIUS Act limit on who can issue, KYC and sanctions screening, and reconciliation back to the ledger. Interviewers want to see that you can hold the upside and the operational cost in the same answer.
The tradeoffs to anchor on
Stablecoin rails are fast and always on, and they cut the cost of moving money across borders. They also add custody risk, chain complexity, and a compliance surface that cards and ACH already handle inside the banking system. A fiat-pegged token has little day-to-day price movement, but reserve quality and de-peg risk are real, and an interviewer may ask how you would protect users if a token slips off its peg. The on-ramp and off-ramp are the parts users actually feel, so a strong product answer gives the ramps as much attention as the transfer. The reasoning an interviewer is testing is whether you can place the rail where it fits rather than treating it as a fix for every payment.
What to study before the loop
Learn the basics of the GENIUS Act: who can issue a payment stablecoin, the reserve and redemption requirements, and the AML and sanctions obligations. Know the major tokens by name and issuer, including USDC, USDT, PYUSD, and RLUSD. Be able to separate the three payment use cases: settlement between businesses, payouts to people, and acceptance from customers. Understand on-ramps, off-ramps, and the FX step, since those are the points of cost and friction. And practice the rail comparison out loud, because the question underneath most stablecoin prompts is when this rail beats a card, an ACH transfer, or a wire.
Stablecoins are now part of the payments toolkit, and interviews rarely ask whether they are an interesting technology. The real questions are where they fit, what they cost to run, and which rules govern the flow. Treat the topic that way, and you will have a much clearer answer.