A stablecoin is supposed to do one thing: stay put at its peg, almost always one US dollar. When it fails to — when it slips to 97 cents, or 80, or worse — that failure is called a depeg, and it can turn a supposedly "safe" holding into a source of real losses in hours. Understanding why depegs happen is essential safety knowledge for anyone using stablecoins, which is nearly everyone in crypto. If the basics of stablecoins are new to you, start with what is a stablecoin, then come back here for the risk side.
What "the peg" means
A stablecoin maintains its value through a peg — a target it is designed to track, typically one dollar. In healthy conditions, market forces and the coin's underlying mechanism keep it hovering right around that target. You can treat one coin as roughly one dollar, which is the whole point.
A depeg is when that link breaks and the coin trades meaningfully away from its target. A slip to $0.99 during a busy moment is minor noise. A slide to $0.90, $0.70, or lower is a serious event that signals the market has lost confidence in the coin's ability to hold its value. The further and longer it drifts, the more alarming.
Why depegs happen
Depegs are ultimately crises of confidence and mechanism. The specific cause depends on what backs the coin, and the three main stablecoin designs fail in different ways.
Fiat-backed coins: reserve doubt and bank runs
Most large stablecoins claim to hold one real dollar (or equivalent safe assets) in reserve for every coin. Their peg rests on the belief that you can always redeem one coin for one dollar. That belief can crack if:
- The reserves are doubted. Rumors or evidence that the issuer does not actually hold enough safe, liquid assets can spark panic.
- A bank holding the reserves fails. If the real-world dollars backing the coin are parked somewhere that gets into trouble, confidence in redemption evaporates.
When holders rush to redeem or sell all at once — a classic bank run — the selling pressure itself can knock the price below a dollar, even temporarily, until confidence returns or the issuer proves the backing.
Algorithmic coins: the death spiral
The most dangerous design is the algorithmic stablecoin, which tries to hold its peg using code and incentives rather than hard reserves. These have a grim history. When confidence wobbles, they can enter a death spiral: the mechanism meant to defend the peg creates more selling, which breaks the peg further, which triggers more selling. Several high-profile algorithmic coins have collapsed from near a dollar to near zero with terrifying speed, wiping out holders who believed "stable" meant "safe." Treat any coin that holds its peg purely through cleverness, rather than assets, with heavy skepticism.
Crypto-collateralized coins: collateral crashes
Coins backed by *other* crypto held as collateral can depeg if that collateral crashes violently and the system cannot liquidate it fast enough to stay adequately backed. These designs deliberately over-collateralize to build a buffer, but an extreme, sudden crash can still overwhelm it.
The warning signs
You cannot predict every depeg, but some conditions raise the risk, and recognizing them is a genuine safety skill — closely related to the instincts in how to spot a crypto scam:
- Opaque or unaudited reserves. If a fiat-backed issuer will not clearly and regularly prove what backs the coin, that is a real risk. Favor coins with transparent, independently verified reserves.
- Yields that are too good. A stablecoin or a "savings" product offering an eye-watering return is compensating you for risk you may not see. Sky-high stablecoin yields have repeatedly preceded blowups.
- Purely algorithmic backing. No hard assets behind the peg is the single biggest structural red flag.
- Thin liquidity. A small, lightly traded stablecoin can lose its peg far more easily than a large, deeply liquid one.
How to protect yourself
Stablecoins are genuinely useful — as a place to sit out volatility, to move value, and to transact. You do not have to avoid them, but you should use them wisely:
- Prefer large, transparent, well-audited stablecoins over obscure or exotic ones. Size and transparency are not guarantees, but they meaningfully reduce risk.
- Understand what backs the one you hold. Fiat reserves, crypto collateral, or an algorithm? The answer tells you how it can fail.
- Be deeply skeptical of high yields. If a stablecoin product pays far more than the norm, ask precisely where that return comes from before trusting it with your money — the same discipline you would apply to staking.
- Do not treat any stablecoin as truly risk-free. "Stable" is a goal, not a guarantee. Never park money you cannot afford to lose in a single stablecoin, however trusted.
- Spread your risk rather than concentrating everything in one issuer.
The takeaway
A depeg is the moment a stablecoin fails at its only job, and it is usually a crisis of confidence in the coin's backing or mechanism. Fiat-backed coins wobble on reserve doubts and bank runs; algorithmic coins can spiral to zero; collateralized coins can buckle when their backing crashes. The word "stable" describes an intention, not a promise. Choose transparent, well-established coins, understand what holds their peg together, treat suspicious yields as the warning they are, and never assume any dollar-pegged token is guaranteed to always equal a dollar. That healthy caution is exactly what keeps your money yours. You can keep an eye on the broader crypto market to see how stablecoins behave when everything else is moving.