What a Stablecoin Is
A token designed to hold a fixed value against a reference asset, most often the US dollar. The design that maintains that peg varies: reserves held by an issuer, collateral locked onchain, or an algorithm adjusting supply. The word describes an intention rather than a guarantee.
Three ways a peg is maintained
Reserve backed. An issuer holds assets, commonly cash and short-term government debt, and issues tokens against them. The peg holds because the issuer will redeem a token for the underlying at par. What you are holding is a claim on that issuer, which makes their solvency, their reserve composition and their willingness to honour redemption the actual risk. This is the most widely used design and the one behind the tokens most payment systems settle in.
Crypto collateralized. Users lock volatile assets into a protocol and mint tokens against them, deliberately overcollateralized so a fall in the collateral's value does not immediately put the system underwater. The peg is maintained by liquidations: if collateral falls too far, positions are closed automatically. The risk is that liquidation depends on functioning markets at exactly the moment markets are least functional.
Algorithmic. Supply expands and contracts by rule, with no meaningful collateral, on the theory that arbitrage will restore the peg. This design has failed repeatedly and at scale, because it relies on continued demand for the token, and demand disappears fastest precisely when the peg is under pressure.
The distinction matters more than the ticker. Two tokens both described as stablecoins can carry entirely different failure modes, and only the mechanism tells you which you are holding.
What can go wrong
Depegging. The market price moves away from the reference. Brief deviations under stress are ordinary and usually recover. A sustained one is a signal that the mechanism is being doubted, not merely that the market is volatile.
Redemption friction. A token may be worth a dollar in principle and not be redeemable by you in practice. Direct redemption is often limited to institutional counterparties above a minimum size, which means most holders exit through a market rather than through the issuer. That distinction is invisible until the day it matters.
Freezing and blacklisting. Most reserve-backed tokens include an administrative ability to freeze balances at specific addresses. This is a compliance feature and it is a real property of the asset: a balance can be made unusable without your involvement.
Regulatory and jurisdictional change. Issuers operate under regimes that evolve, and a rule change can alter redemption, reporting or availability without any technical failure.
Bridge and wrapper risk. A token representing a stablecoin on a different network is a claim on a bridge, not on the original issuer. It carries all the original risk plus the bridge's, and the two are frequently conflated because the names look similar.
Stable is relative to a reference
A dollar-referenced token is stable against dollars and moves against everything else. If your costs are in another currency, the token is not stable from where you are standing. This is obvious stated plainly and it is routinely forgotten in cross-border contexts, where a stable settlement asset is quietly a currency exposure.
Why machine payments use them
Autonomous software transacting continuously needs one property above all: an amount agreed now must mean the same thing when it settles, and again when it is reconciled.
A volatile asset makes that impossible to reason about. A budget denominated in something that moves is not a budget, and a price quoted in it is not a price. Every downstream mechanism, spending caps, per-call pricing, reconciliation, accounting, assumes the unit holds still.
That is the whole reason stablecoins matter for agent payments, and it is a narrower claim than the ones usually made for them. The value is a predictable unit of account with programmable transfer, not the token as an asset.
Which also sets the terms for choosing one. Prefer the design whose failure mode you can actually reason about and monitor. Understand whether you can redeem or only sell. Know that balances can be frozen and decide whether that is acceptable for your use. And keep the float small enough that any of these being wrong is survivable, which is the same discipline that applies to any bounded spending authority.
This is general information rather than financial advice, and the specifics differ by issuer and by jurisdiction.
Frequently asked questions
- What is a stablecoin?
- A token designed to hold a fixed value against a reference asset, usually the US dollar. The mechanism maintaining that peg varies between reserves held by an issuer, crypto collateral locked onchain, and algorithmic supply adjustment, and the mechanism determines how it can fail.
- Are all stablecoins backed by dollars?
- No. Reserve-backed tokens are, typically by cash and short-term government debt held by an issuer. Crypto-collateralized tokens are backed by volatile assets held in excess of the tokens issued. Purely algorithmic designs hold no meaningful collateral and have failed repeatedly at scale.
- What does depegging mean?
- The market price moving away from the reference value. Brief deviations under stress are ordinary and usually recover. A sustained deviation signals that the maintaining mechanism is being doubted, which is a different and more serious condition than ordinary market volatility.
- Why do AI agent payments use stablecoins?
- Because an amount agreed now must mean the same when it settles and again when it is reconciled. Spending caps, per-call pricing and accounting all assume the unit holds still. The value is a predictable unit of account with programmable transfer, not the token as an asset.