Why Stablecoins Depeg: The Four Failure Modes
Stablecoins break in four distinct ways: reserve failure, liquidity failure, collateral failure and reflexive collapse. Knowing which one you are watching tells you whether a depeg recovers or never does.
A depeg is not one event. A stablecoin trading at $0.98 might recover fully within days, or it might be the first hour of a collapse to zero. The price alone does not tell you which.
What tells you is the mechanism. There are four, and they behave very differently.
1. Reserve failure
The backing is not there, or not accessible. The issuer either does not hold what it claims, or holds it somewhere that has become unreachable.
USDC in March 2023 is the clean example. The reserves existed, but a portion sat in a bank that failed on a Friday. The token traded to about $0.87 over a weekend and returned to par once access was confirmed on Monday. Nothing was actually missing — the market was pricing the probability that it might be.
How to read it: ask whether the assets are gone or merely stuck. Stuck recovers. Gone does not. This is why reserve composition and custody matter more than the headline total, and why proof of reserves is worth understanding before you need it.
2. Liquidity failure
The backing is fine. The market is not. There are more sellers than the available depth can absorb, so the price slips even though redemption remains good.
This is the most common depeg and the least dangerous. It usually shows up as a small discount on one venue while other venues trade closer to par — a strong tell, because a genuine reserve problem prices identically everywhere.
How to read it: compare across venues. Fragmented pricing means a liquidity event. Uniform pricing means the market believes something about the issuer.
3. Collateral failure
Specific to over-collateralised designs. The collateral falls faster than liquidations can process, and the system briefly holds less value than it has issued.
Network congestion is what turns this from manageable to serious. Liquidations compete for blockspace with everyone else exiting at the same moment, so the mechanism that is supposed to protect solvency is slowest exactly when it is needed most.
How to read it: watch the collateral ratio and whether liquidations are clearing. A system that is over-collateralised and liquidating normally is working as designed, even if uncomfortable.
4. Reflexive collapse
The failure mode with no floor. The peg depends on confidence, and the mechanism defending it makes things worse once confidence goes.
Terra's UST is the case study. UST could be redeemed for a dollar of LUNA, so as UST fell, the system minted increasing amounts of LUNA into a market that was already selling. Supply exploded, price collapsed, and the redemption backstop became worthless precisely when it was needed.
How to read it: if the thing backing the stablecoin is a token whose value depends on the stablecoin working, that is reflexive. There is no recovery path once it turns.
Telling them apart in real time
Three questions, in order.
- Is the backing external to the system? Dollars and treasuries are external. A sibling token is not. External backing can recover; reflexive backing usually cannot.
- Is redemption still working? If holders are redeeming at par, the discount is a liquidity or confidence event, not an insolvency.
- Is the discount uniform across venues? Fragmented means liquidity. Uniform means the market has a view on solvency.
What this means for yield
Depeg risk is the risk you are usually being paid for when a stablecoin strategy offers an unusually high return. That is not automatically bad — it is a real risk with a real premium — but it should be a decision rather than a surprise.
The practical rules: do not hold one issuer exclusively, treat any yield far above short-term government rates as compensation for something, and remember that in a genuine depeg the exit liquidity disappears at the same moment you want it. See earning yield on stablecoins and risk management rules.
Does regulation help?
Partly. MiCA imposes reserve quality, redemption and reporting requirements on issuers serving EU users, which directly targets failure modes one and four — it makes reserve composition auditable and effectively rules out uncollateralised algorithmic designs. It does nothing about liquidity failures, which are a market-structure problem.
Regulated issuers also carry obligations around who they onboard and monitor, which is why KYC infrastructure sits alongside reserve attestation in any compliant issuance stack. Our MiCA-compliant stablecoins guide has the detail.
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