Stablecoins

Definition

Stablecoins are tokens engineered to hold a fixed value against a reference asset — overwhelmingly the US dollar — by one of three mechanisms: fiat-reserve backing (issuer holds cash and Treasuries against tokens outstanding), crypto-collateralized overbacking, or algorithmic supply adjustment. They are the cash leg and settlement rail of crypto markets: most spot and derivatives volume on crypto venues is priced and settled against a stablecoin, not against bank dollars — which makes stablecoin integrity a SYSTEM property of the asset class, not one product’s detail.

How it works / structure

• Fiat-reserve model: issuer mints tokens against received dollars and redeems at par; the token is an issuer liability whose quality is the reserve portfolio plus the redemption promise. The PWG report (2021) documents the run-risk framing: a stablecoin is economically a demand deposit without deposit insurance. The GENIUS Act (2025) created a federal payment-stablecoin regime — permitted issuers, full reserve requirements, redemption rights — moving the largest dollar stablecoins toward regulated-liability status (crypto-regulation-us).
• Crypto-collateralized: tokens minted against on-chain collateral exceeding face value, with automated liquidation of underwater positions; stability depends on collateral volatility and liquidation-mechanism throughput under stress.
• Algorithmic: supply expands and contracts against a paired asset with no external backing. The May 2022 Terra/UST failure — a multi-billion-dollar token declining to near zero within days, with fraud charges following (SEC v. Terraform Labs) — is the canonical exhibit that the mechanism is reflexive: the peg holds while confidence holds.
• Market role: quote currency on most venues, collateral on derivatives venues (crypto-perpetual-futures), and the arbitrage rail moving value across fragmented exchanges (crypto-spot-market-structure).

When it applies

Any crypto market thesis touches stablecoins implicitly: they are the pricing unit, the funding leg, and the stress-transmission channel. Explicit theses include peg-stress monitoring (secondary- market price vs par as a systemic gauge), issuance/redemption flows as a demand proxy (cited with venue data caveats), and regime analysis — a large depeg event is a crypto-wide liquidity event, not an isolated one.

Risk profile & failure modes

• Run dynamics: par redemption promises meet a reserve portfolio with any duration or credit risk — classic run structure (PWG 2021); secondary-market discounts appear faster than redemptions process.
• Reflexive designs fail completely: the algorithmic class’s failure mode is not a small discount but collapse (Terra/UST 2022) — documented, not hypothetical.
• Reserve opacity: Griffin-Shams (2020) is the peer-reviewed treatment of unbacked-issuance concerns in an earlier era of the largest stablecoin; disclosure has improved and the GENIUS regime mandates reserves, but reserve attestation quality varies by issuer and era — claims about backing are dated claims.
• Depeg contagion: because stablecoins are the market’s cash leg, a peg break marks every stablecoin-quoted book simultaneously — correlation to par is not diversification (port-correlation-budgets).

Evidence & limits

Run-risk framing and reserve requirements are government- documented (PWG 2021; GENIUS Act 2025). The Terra collapse and its fraud findings are public record. Griffin-Shams is peer- reviewed evidence on historical issuance practices; its conclusions are contested by the issuer and specific to its sample period. Whether any given peg holds through the next stress is exactly the kind of claim the platform requires a falsifier for, not an assumption.

Falsifiable-thesis examples

Illustrations only, not signals:

• “The largest dollar stablecoin trades within 50 bps of par on every day of the next quarter (peg-integrity thesis)” — falsified by any wider print in the consolidated price series.
• “Aggregate stablecoin float contracts during the next crypto drawdown exceeding 20% (flight-to-bank-dollars thesis)” — falsified by issuance data over the episode.

Cross-references

• Asset-class frame: ext-crypto; issuer-layer taxonomy: crypto-coins-vs-tokens
• Where the cash leg matters: crypto-spot-market-structure, crypto-perpetual-futures (collateral), ms-liquidity
• Legal regime: crypto-regulation-us; stress propagation: regime-volatility