What the “stablecoin sandwich” leaves out

Definition

A stablecoin sandwich is industry shorthand for a payment in which fiat is converted into a stablecoin, the stablecoin moves between institutions on a ledger, and it is converted back into fiat for the recipient – fiat in, stablecoin settlement, fiat out. The term describes the shape of the flow. It does not describe the licensed institutions, liquidity, FX, identity checks, reconciliation and domestic payout that make the flow a payment.

A stablecoin sandwich describes fiat at both ends of a payment, with a stablecoin used for settlement in between. In the institutional model considered here, a regulated digital currency carries value between participants while the sender and recipient use familiar payment channels.

For an institution evaluating the model, the next questions concern the participants: who converts the money, who funds each position, who pays out and who responds to a failure. The term describes a payment structure and is unrelated to a sandwich attack in decentralised finance.

The shape, stated plainly

Three steps. An on-ramp converts the sender’s fiat into a stablecoin – a regulated digital currency issued by a licensed institution. The stablecoin moves on a ledger from one institution’s account to another’s; that transfer is the settlement. An off-ramp converts the stablecoin back into fiat and a domestic institution pays the recipient. Sender and recipient see a bank payment. The stablecoin exists only in the middle mile, between institutions.

This model is useful when institutions want to change the settlement leg while keeping collection and payout in fiat. Its suitability depends on the funding arrangements, licensed participants and customer requirements of the particular flow.

Conversion at both ends

The two conversions are not technical steps. They are regulated activities performed by institutions with licences, balance sheets, operating hours and capacity limits. The on-ramp is whoever accepts fiat and delivers the settlement asset; the off-ramp is whoever accepts the settlement asset and pays out fiat. Each is a counterparty with its own risk, its own cut-offs and its own failure modes.

A corridor is only as strong as its weaker ramp. Ledger settlement in seconds is worth little if redemptions are batched overnight, if the off-ramp’s capacity is a fraction of the corridor’s volume, or if one ramp sits in a jurisdiction where the asset’s legal status is unresolved. In practice the ramps, not the ledger, set the corridor’s real speed, cost and reliability.

What the term leaves out

The functions below need to be addressed across the full flow. Their allocation can change with the settlement model. Establish an owner for each and agree how the participants will work together.

• Licensing

  Which activities are regulated on each leg, who holds the licences, and how the asset is classified in every jurisdiction the payment touches. The ledger takes none of this.

• Identity and screening

  KYC on senders, KYC on recipients, sanctions screening in flight. These belong to the network and the bank, as they always did.

• Liquidity

  Someone acquires the settlement asset ahead of the payment and someone holds local currency to pay out. The funding model is a corridor decision, not a property of the token.

• FX

  A stablecoin is denominated in one currency. If the payment starts or ends in another, conversion happens and someone carries the exposure. In thin or managed currency markets this is often the binding constraint.

• Custody and keys

  Holding the settlement asset means controlling keys. Signing governance, rotation, recovery and access reviews are a permanent operational cost with an auditable owner.

• Issuer risk

  Reserve composition, redemption terms, supervision and the issuer’s own freeze and clawback powers. Counterparty risk, assessed as counterparty risk.

• Reconciliation

  A shared ledger record improves one input. Each institution still reconciles it to its own books, messages, FX positions and payout confirmations.

• Domestic payout

  The last mile is a licensed domestic institution paying local currency over rails the recipient already uses. Without it, the settlement asset reaches an account balance, not a person.

• Responsibility

  When a payment fails, is delayed or is challenged by a regulator, a named institution answers. The ledger holds no licence and owns no obligation.

Assessing the issuer

For an issuer-backed settlement asset, institutions need to establish the claim on the issuer, reserve arrangements, redemption terms and applicable supervision. Putting one in the middle of a payment means every institution in the corridor takes exposure to that issuer for as long as it holds the asset – and takes on the issuer’s own controls, including its power to freeze or claw back balances.

The practical consequence is that instrument choice comes before chain choice. An institution should first identify the regulated money that matches its currency, counterparties and legal perimeter, and only then ask which ledgers that money can move on. A corridor designed around a ledger, with the issuer chosen afterwards, has the decisions in the wrong order.

Prefunding moves; it rarely vanishes

The most common claim made for the sandwich is that it eliminates prefunding. The honest version is narrower. Prefunding exists because someone must hold the destination currency before they are sure they have been paid, or because prepaid positions are needed in several currencies at once. Faster and more certain settlement can shrink that window, and a common settlement asset can consolidate several prepaid positions into one.

But somebody still acquires the settlement asset ahead of the payment, and somebody still holds local currency to pay out. The capital has changed instrument and location; it has not disappeared. Partners in the Ethiopia corridor have said publicly – the Quantoz CEO, in the Cooperative Bank of Oromia announcement – that regulated digital euro can reduce the need for costly pre-funding. The effect on capital requirements must be assessed across the full corridor, including the settlement asset and local-currency payout positions.

A worked example: Europe → Ethiopia

The corridor that TerraPay, Cooperative Bank of Oromia and Quantoz Payments launched on 6 May 2026 is, in shorthand, a sandwich. TerraPay’s cross-border payments network carries euro-denominated remittances from Europe. Regulated euro e-money from Quantoz Payments is the settlement asset. Xahau is the ledger on which it moves between institutions. Cooperative Bank of Oromia pays the recipient in Ethiopian birr. The customer on each side sees a remittance, not a token.

TerraPay’s announcement also describes the work around the settlement leg: INFTF and TerraPay worked with Ethiopian financial authorities to establish the regulatory and technical framework. The ledger operates alongside the existing compliance, licensing and operational frameworks of the participants. The corridor illustrates how institutional coordination makes the settlement model usable.

A better question than “is it a sandwich”

An institution assessing a proposed corridor needs to establish who holds the licence on each leg, who issues and redeems, who funds the position and carries the FX, who screens, who pays out, who reconciles, who reports, and what halts when one of them fails. The corridor readiness framework brings these responsibilities into fifteen decisions.

Those answers provide the basis for assessing the flow, identifying missing participants and deciding what needs further design.