The peg is the target price a stablecoin is designed to maintain, almost always $1.00 USD. The "peg holds" when the market price stays at or very near $1. It "depegs" when supply/demand pressure, loss of confidence, or mechanical failure pushes the price away from $1. How the peg is maintained depends on the stablecoin type: redemption arbitrage for fiat-backed, liquidation mechanics for crypto-backed, or algorithmic expansion/contraction.
What Is a Stablecoin Peg?
3 min read
The short version
The peg is the promise that 1 stablecoin = 1 dollar. Different stablecoins keep that promise in different ways. Fiat-backed ones say "you can always hand this back to us for a real dollar." Crypto-backed ones say "there is always more collateral than debt in the system." Algorithmic ones say "the code will balance supply and demand." When the market doubts any of these promises, the peg breaks.
How It Works
Peg maintenance mechanisms: (1) Fiat-backed (USDC): if price < $1, arbitrageurs buy cheap on market and redeem for $1 from issuer (profit). If price > $1, they mint new tokens for $1 and sell on market (profit). Both actions push price back to $1. (2) Crypto-backed (DAI): if DAI > $1, governance lowers the Stability Fee (cheaper to mint DAI, more supply). If DAI < $1, governance raises rates (less supply, more demand to hold). Liquidation mechanics ensure backing always exceeds debt. (3) Algorithmic: expand/contract token supply mechanically. As discussed in the algorithmic stablecoin article, this mechanism is fragile under stress. Normal deviations: fiat stablecoins routinely trade $0.999-$1.001 (this is healthy, not concerning). Deviations of 1-2% are unusual and signal stress. Deviations of 5%+ are crises.
USDC depeg and recovery during SVB crisis (March 2023)
Friday March 10, 2023: Circle discloses $3.3B of reserves at Silicon Valley Bank (which just failed). Market panics. USDC sells off on DEXs. Saturday: USDC hits $0.87 on Curve. Users swap billions of USDC for DAI and USDT. Curve's 3pool becomes 90%+ USDC (everyone dumping it). Sunday evening: US government guarantees all SVB deposits. Monday: Circle confirms reserves are fully accessible. USDC returns to $0.998 within hours as arbitrageurs pile in. By Tuesday: back to $1.000 flat. Total depeg duration: ~60 hours. Lesson: even the best-designed peg can temporarily fail if the underlying banking infrastructure is questioned, but recovery can be swift once the fundamental backing is confirmed safe.
What People Get Wrong
A stablecoin peg can never break
Pegs are maintained by active mechanisms (arbitrage, governance, algorithms). If those mechanisms are overwhelmed or the underlying backing is called into question, the peg breaks. It happens. UST went to $0. USDC went to $0.87. Even USDT has dipped to $0.95 historically.
A brief depeg means the stablecoin is worthless
Brief depegs (hours to days) driven by temporary events often resolve fully. The March 2023 USDC depeg was temporary. What matters is: did the fundamental backing survive? If yes, the peg typically recovers. If the backing itself is gone (like UST), recovery is impossible.
The peg is maintained by the stablecoin company 24/7
For fiat-backed coins, the company enables redemption (which creates the arbitrage opportunity), but the actual market-price maintenance is done by profit-seeking arbitrageurs, not by the issuer actively buying/selling on exchanges. The system is designed to be self-correcting through rational market participants.
Keep Reading
Sources & Further Reading
- Curve 3pool (Peg Monitor)
The primary stablecoin liquidity pool where depeg events are first visible
Questions People Also Ask
- Should I sell if a stablecoin depegs slightly?
- It depends on why. If the depeg is from temporary market inefficiency or a solvable banking issue (like USDC/SVB): selling at a discount locks in a loss that may recover within days. If the underlying mechanism is fundamentally broken (like UST/LUNA): exit immediately. The challenge is determining which scenario you are in, in real time.
- How can I monitor stablecoin peg health?
- DefiLlama (stablecoins page), Curve pool ratios (imbalanced pools indicate stress), and CoinGecko/CoinMarketCap price pages. If a stablecoin's Curve pool becomes >80% one asset, that is an early warning sign of selling pressure.
- Do stablecoins pegged to other currencies exist?
- Yes. EURS (Euro), XSGD (Singapore Dollar), GYEN (Japanese Yen), and others exist but with much smaller market caps and liquidity than USD stablecoins. The dollar dominates because most crypto trading pairs and DeFi protocols are dollar-denominated.