Development of a Stablecoin Peg Stabilization System
UST/LUNA in May 2022 lost its dollar peg in 72 hours — $18 billion evaporated. The mint/burn mechanism via LUNA couldn't withstand coordinated liquidity attack: UST sale pressure collapsed price, LUNA mint for peg recovery created inflation, inflation crashed LUNA, reducing mint/burn effectiveness — death spiral. This is not implementation bug, this is architectural failure of stabilization mechanism.
Design peg stabilization system by answering: what happens in $100M attack over 24 hours?
Stabilization Mechanisms: Trade-offs
Overcollateralized (MakerDAO/DAI Model)
User locks ETH at 150% of borrow, mints DAI. When ETH drops below liquidation threshold — position liquidated, DAI bought from market. Peg holds while collateral > debt and liquidations work fast.
Vulnerability: rapid collateral price drop (>30% in hours) outpaces liquidations — bad debt forms. MakerDAO solved via Emergency Shutdown and Stability Fee as auto-regulator. If DAI > $1.00, Stability Fee drops — cheaper borrowing, supply grows, price falls. If DAI < $1.00, Fee rises — less minting, less supply, price rises.
This mechanism works reliably but slowly (hours, not minutes) and requires active governance for parameter tuning.
Algorithmic Stabilization (Frax Model)
Frax USDC — partially collateralized, partially algorithmic. When peg >$1.00 system lowers collateral ratio (less USDC in backing), when peg <$1.00 — raises. AMO (Algorithmic Market Operations) controllers deploy reserves in Curve/Aave for yield generation and peg support.
More capital-efficient than overcollateralized, but requires precise management and sufficient liquidity in base pools. Frax works because it has deep Curve pool and significant Treasury reserves.
PSM (Peg Stability Module)
Direct 1:1 swap of stablecoin to another stablecoin (e.g., sUSD to USDC) via PSM without slippage. Arbitrageurs maintain peg automatically: if sUSD < $1.00, buy cheap, swap to USDC via PSM 1:1, profit. If sUSD > $1.00, buy USDC, swap to sUSD, sell higher.
PSM most efficient for short-term stabilization, but requires USDC/USDT reserves. MakerDAO uses PSM as main DAI buffer.
What We Build in Practice
For new stablecoin protocol we recommend multi-level system:
First Level — Overcollateralization with Dynamic Stability Fee. Base mechanism proven over time. Interest rate controller via PI (Proportional-Integral) regulator: peg deviation from $1.00 automatically changes rate. Solidity implementation with Chainlink TWAP for peg measurement.
Second Level — PSM with Limited Capacity. PSM with cap on USDC reserve volume (e.g., 20% of total supply). When cap reached PSM disables — protects from complete collateral displacement.
Third Level — Circuit Breaker. If peg deviates >5% in 1 hour — automatic mint pause. Liquidations continue, new positions blocked. Gives governance time to respond without panic.
Key Contracts
StablecoinEngine — core logic, vault management
StabilityFeeCollector — accrual and distribution of Stability Fee
PegStabilityModule — direct 1:1 swap to reserve token
PriceOracle — aggregator of Chainlink + Uniswap V3 TWAP
LiquidationEngine — collateral position liquidations
RateController — PI-regulator of Stability Fee
Oracle for measuring own peg — separate task. Chainlink doesn't provide feed for new stablecoin. Use Uniswap V3 TWAP on stablecoin/USDC pair with 30-minute period — long enough for flash loan manipulation protection, short enough for real depeg reaction.
Risks We Build Into Architecture
Governance Attack. If governance token concentrated, attacker via flash loan gains voting power and changes parameters (raise collateral factor, remove circuit breaker). Protection: timelock on all critical parameters (minimum 48 hours), snapshot voting instead of on-chain for discussion.
Oracle Manipulation. Flash loan + Uniswap pool manipulation + price-dependent function calls. Protection: TWAP minimum 15 minutes, secondary oracle as check.
Liquidity Crisis. Mass liquidations dump collateral on market, its price drops, triggering more liquidations. Protection: auction-based liquidation (Dutch auction) instead of immediate market sale, surplus buffer as bad debt buffer.
Timeline Guidance
Basic overcollateralized system with Stability Fee and liquidations — 4–6 weeks. Full stack with PSM, AMO, PI-regulator, and governance — 8–14 weeks. External audit before mainnet — 4–6 more weeks. For stablecoin protocols audit is not optional.