Stability Mechanisms
Every stablecoin answers the same question differently: "Why is this token worth $1?" The answer determines everything - capital efficiency, decentralization, censorship resistance, and systemic risk. No single design is optimal for all use cases. Below we simulate each mechanism's core dynamics interactively, so you can feel where the leverage and risk lives.
Collateral-Backed: DAI-Style Vault Simulator
Over-collateralized stablecoins like DAI work like a CDP (Collateralized Debt Position): deposit ETH as collateral, mint DAI against it at a ratio enforced by the protocol. The liquidation engine auto-closes positions when collateral falls below the minimum ratio. Explore the vault mechanics below.
Fiat-Backed: How USDC/USDT Maintain the Peg
Fiat-backed stablecoins are the simplest design: every token is matched 1:1 by real assets in a bank account. The peg is maintained by (1) direct redemption: any holder can redeem 1 USDC -> $1 from Circle's bank account, and (2) arbitrage: when USDC falls below $1, buyers bid it up. The key risk is banking counterparty failure - which is exactly what happened to USDC at SVB.
~25% Overnight repos
~15% Cash at US banks
Monthly attestation from Grant Thornton. SOC 2 Type II in progress.
~20% Bitcoin (held as reserve)
~10% Repo / secured loans
~5% other assets
Quarterly attestation only. No full audit ever completed.
Banking license revocation
Regulatory seizure
FDIC insurer delay (weekend gap)
The peg holds only if reserves are accessible AND timely.
Algorithmic: Terra UST - Death Spiral Anatomy
Terra UST used seigniorage: new LUNA tokens were minted to absorb UST supply imbalances. The arbitrage loop worked perfectly in calm markets - until the first major shock broke confidence and the spiral accelerated faster than any intervention could stop.
Hybrid: FRAX Fractional-Algorithmic Design
FRAX (Fractional Reserve AMO - Algorithmic Market Operations) pioneered the 'fractional' model: always partially backed by collateral, with FXS absorbing the unbacked remainder. Unlike Terra, FRAX has a redemption backstop via USDC that limits downside.
Yield-Bearing: USDe & sUSDe Delta-Neutral Mechanics
Ethena's USDe introduced the first genuinely decentralized synthetic dollar: a delta-neutral structure that holds spot ETH and shorts perpetual futures of equal size. The short perpetual funding rate becomes the yield. sUSDe wraps USDe with Ethereum staking rewards added on top. Neither is a traditional stablecoin - they are a new risk-managed yield instrument.
? Peg Stability Module (PSM) vs. Delta-Neutral vs. Reserve Comparison
Different stablecoins use different mechanisms to maintain the peg - and none are identical. The table below compares how each approach responds to depeg scenarios.
| Mechanism | Example | Peg Defense Tool | Depeg Response | Max Depeg Depth | Systemic Risk |
|---|---|---|---|---|---|
| Collateral | DAI (ETH vault) | Auto-liquidation closes CDP | 150%+ collateral absorbs shocks | ~35% ETH drawdown before liq. | ETH correlation risk |
| Fiat Reserve | USDC | 1:1 USDC->USD redemption | FDIC backstop (SVB case) | $0.87 (SVB, recovered 72h) | Bank counterparty |
| PSM | DAI PSM | Swap USDC?DAI 1:1 for fee | Arbitrage loop restores peg | Only as deep as USDC holds | USDC concentration |
| Algorithmic | LUNA/UST (defunct) | Burn LUNA -> mint UST | LUNA hyperinflation spiral | Total loss (Terra case) | Confidence bootstrap paradox |
| Delta-Neutral | USDe | Spot ETH + short perpetual | Funding rate shifts, not peg tool | Depeg not primary risk | Exchange counterparty |
| Fractional | FRAX | USDC recourse + AMO deploy | Protocol buys FRAX -> USDC | Limited by USDC reserve depth | FXS dilution if too aggressive |
Interactive Peg Deviation Simulator
Every stablecoin faces peg deviations in the market. How does the mechanism respond? Move the market price slider to see arbitrage opportunity and protocol response for each mechanism type.
Deep Dive: Why No Single Design Wins
Each stablecoin mechanism optimizes for different trade-offs. The 'best' stablecoin depends entirely on your use case: trading, long-term savings, DeFi lending, cross-border payments, or institutional custody. Below is the decision framework.
sUSDe - high yield + decent peg stability; good for earn strategies while remaining liquid.
USDC has better regulatory standing; USDT has deeper Curve liquidity. Both work for DEX trading.
USDe - exchange-decentralized; holds native ETH (not a bridge). Good for DeFi-native strategies.
Both survive regulatory black swan better than fiat-backed alternatives.
DAI DSR (~4-8% APY) - decentralized, insured by MKR governance, no counterparty.
sUSDe yield comes from perp funding; DSR comes from DeFi lending. Different risk profiles.
The lesson: you need some real value (collateral, not just confidence) to absorb the first wave of panic selling.
Real-World Stress Tests: What Actually Broke the Peg
Stablecoin theory is clean. Reality is messier. Every major stablecoin has faced a stress test that revealed which risks the theoretical model had underweighted.