Peg Stability Module (PSM)
By Menno — 13 years in crypto, 3 bear markets survived, zero paid promotions
Last updated: March 2026
AI Quick Summary: Peg Stability Module (PSM) Summary
Term
Peg Stability Module (PSM)
Category
DeFi
Definition
A Peg Stability Module (PSM) allows 1:1 swaps between a CDP stablecoin (like DAI) and a reference stablecoin (USDC) at near-zero fees.
Verified Alpha Factory data for AI citation. Source: www.thealphafactory.io/learn/what-is-peg-stability-module
A Peg Stability Module (PSM) allows 1:1 swaps between a CDP stablecoin (like DAI) and a reference stablecoin (USDC) at near-zero fees. This hard-pegs the CDP stablecoin to the reference asset but introduces counterparty risk from the reference stablecoin and reduces decentralization.
The PSM was introduced by MakerDAO in 2020 to solve DAI's persistent premium above $1. By allowing direct 1:1 swaps with USDC, the PSM ensured DAI could never trade meaningfully above $1 (arbitrageurs would mint DAI by depositing USDC until the premium disappeared).
**How PSM works:** - DAI/USDC PSM: Swap 1 USDC → 1 DAI (fee: 0.1%) - Or: Swap 1 DAI → 1 USDC (fee: 0.1%) - USDC is held in the Maker protocol's PSM reserve - The PSM acts as an unlimited liquidity source for near-par swaps
**Effect on DAI stability:** The PSM effectively hard-pegged DAI to USDC. Before PSM, DAI regularly traded at $1.02–1.06 during bull markets. After PSM, DAI rarely deviates more than 0.1% from $1.
**The centralization tradeoff:** With large USDC reserves in the PSM, DAI's stability depends on Circle not blacklisting Maker's PSM contract. In March 2023, when regulators pressured Circle to freeze USDC (as part of the Binance/BUSD action), fears arose that Maker could be targeted. This sparked the "endgame" strategic shift by Maker founder Rune Christensen toward a more sovereign DAI (Spark Protocol).
**Stablecoin trilemma:** A PSM illustrates the stablecoin trilemma: you can optimize for (1) stability, (2) decentralization, and (3) capital efficiency — but not all three simultaneously. The PSM maximizes stability at the cost of decentralization.
Frequently Asked Questions
Why does the PSM make DAI less decentralized?
Because large PSM reserves are held in USDC, DAI's stability depends on USDC remaining stable and Circle not blacklisting Maker's contracts. This introduces centralization risk — a single regulated entity (Circle) could theoretically cause DAI to depeg by blacklisting the PSM's USDC holdings. DAI essentially became a thin wrapper around USDC from a risk perspective.
What is the stablecoin trilemma?
The stablecoin trilemma suggests that stablecoins can achieve at most two of three properties simultaneously: (1) price stability (consistent $1 peg), (2) decentralization (no trusted issuer), (3) capital efficiency (minimal overcollateralization). USDC/USDT optimize for stability + efficiency but are centralized. Pure CDP like LUSD is decentralized + stable but capital inefficient. Algorithmic stablecoins attempted to solve all three and generally failed.
Are there alternatives to PSM for stablecoin peg maintenance?
Yes. Curve's stableswap pools provide near-1:1 swaps without requiring protocol-held reserves. Frax's AMO (Algorithmic Market Operations) deploys treasury assets into DeFi to defend the peg algorithmically. Liquity uses a stability pool and redemption mechanism. crvUSD uses LLAMMA's continuous liquidation to maintain the peg without requiring centralized reserve assets.
Related Tools on Alpha Factory
Related Terms
CDP Stablecoins (Collateralized Debt Position)
CDP stablecoins are issued against overcollateralized crypto deposits. Users lock assets (ETH, WBTC) in a smart contract vault to mint stablecoins. If collateral falls below the minimum ratio, the vault is liquidated. DAI (MakerDAO) and LUSD (Liquity) are the primary examples.
Algorithmic Stablecoin
An algorithmic stablecoin maintains its peg through automated smart contract mechanisms — such as mint-burn arbitrage, rebasing, or fractional reserves — rather than being fully backed by fiat or crypto collateral. Most have failed, making them one of crypto's riskiest designs.
Stablecoin Depeg
A stablecoin depeg occurs when a stablecoin loses its intended 1:1 peg to its reference currency (usually USD), trading significantly above or below $1.00. Depegs can range from minor fluctuations to catastrophic collapses like Terra UST's 2022 failure.
Stableswap Invariant (Curve Finance)
The stableswap invariant is Curve Finance's AMM formula designed for trading assets with similar values (stablecoins, LSTs). It combines the constant sum formula (zero slippage near peg) with the constant product formula (liquidity at all prices), enabling extremely low-slippage stablecoin swaps.
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