What is a stablecoin?
A stablecoin is a crypto token designed to hold a steady value, usually one US dollar. Here is how the main types work, how they fail, and what to check.
A stablecoin is a crypto token engineered to stay at a fixed value, almost always one US dollar. It lets people hold and move dollars on a blockchain without touching a bank directly, so a dollar can settle across the world in minutes at any hour.
Stablecoins are the quiet workhorse of crypto. By mid-2026 more than $300 billion of them were in circulation, and far more value settles through them than through most of the assets that get the headlines. Roughly half sits on Ethereum and close to a third on Tron, which has become the default rail for cheap dollar transfers.
That size makes the question of how they hold their value, and how they lose it, one of the most important in the whole market. This page walks through the main types, the mechanism that keeps the price at a dollar, how that mechanism breaks, and what to check before you trust one.
The main types of stablecoin
Fiat-backed stablecoins hold reserves of cash and short-term government debt, and issue one token per dollar held. They are the simplest and by far the most widely used. Their safety depends entirely on the quality of those reserves and on whether you can actually redeem a token for a real dollar.
Crypto-collateralised stablecoins lock up other crypto assets as backing, over-collateralised on purpose so that a fall in the collateral's price does not immediately break the peg. Put up $150 of crypto to mint $100 of stablecoin, and there is a buffer before the system is underwater.
Algorithmic stablecoins try to hold the peg with supply rules and little or no full backing, expanding and contracting the token supply to nudge the price. This design has failed repeatedly and spectacularly, wiping out tens of billions in a single case, and deserves deep scepticism no matter how clever the mechanism sounds.
What keeps a stablecoin at a dollar?
The peg holds through redemption and arbitrage. If a fully backed token trades at 99 cents, a trader can buy it cheap, redeem it with the issuer for a full dollar of reserves, and pocket the difference. That buying pressure pushes the price back toward a dollar. The same works in reverse above a dollar.
The whole mechanism rests on one word: redeemable. If redemption is real, fast, and open to enough participants, the peg is a mechanism. If you cannot actually get your dollar back, the peg is just a promise, and promises break under stress.
That gap between promise and mechanism is where most stablecoin failures live. A token can look pegged for months, right up until a wave of holders tries to redeem at once and discovers the reserves are illiquid, encumbered, or simply not there.
How stablecoins fail
There are two failure modes. The first is a reserve failure: the assets backing the token turn out to be worth less than the tokens outstanding, or cannot be sold fast enough to meet redemptions. Confidence goes, everyone heads for the exit at once, and the price drops below a dollar and stays there.
The second is a design failure, specific to algorithmic coins that lean on a companion token to absorb shocks. When confidence cracks, the system prints more of the companion token to defend the peg, that token collapses under its own supply, and the two spiral down together. This is what happened in the largest stablecoin failure to date, which erased its value in days.
The practical lesson is that a stable price today tells you little about resilience tomorrow. What matters is what happens on the worst day, when everyone wants out at the same time.
What to check before trusting one
Ask three questions: what backs it, who holds and audits the reserves, and how quickly you could get your dollar back if everyone asked at once. Look for regular, independent attestations of reserves rather than a marketing page that says 'fully backed'.
Prefer issuers that hold plain cash and short-dated government debt over exotic or illiquid assets. In stablecoins, boring reserves are a feature, not a knock. And prefer designs where redemption is open and tested, not theoretical.
Finally, size your exposure to the risk. A fully reserved, audited, redeemable stablecoin is a reasonable place to park dollars on-chain. An unaudited or algorithmic one paying an eye-catching yield is a bet, and the yield is the compensation for a risk that occasionally comes due all at once.
Frequently asked questions
Are stablecoins safe?
It depends entirely on what backs them and whether you can redeem. A fully reserved, audited, fiat-backed stablecoin carries very different risk from an algorithmic one with no real backing. Always check the reserves and the redemption process before trusting one with size.
Why do people use stablecoins instead of dollars?
They move at the speed of the internet, settle in minutes across borders, and work without a traditional bank account or banking hours. That is why businesses moving money internationally, not just speculators, drive much of the demand.
Which is the biggest stablecoin?
By circulating supply the largest are dollar-backed tokens issued by a small number of firms. The concentration matters: a problem at one large issuer would ripple across the whole market, which is part of why regulators watch reserves so closely.
Can a stablecoin lose its peg?
Yes. If reserves are poor, redemption stops working, or confidence collapses, a stablecoin can trade below a dollar, sometimes permanently. Over-collateralised and fully reserved designs are far more resilient than algorithmic ones.
Do stablecoins pay interest?
The token itself usually does not. Any yield you see is being paid by a platform lending your stablecoin out or running a strategy with it, which adds that platform's risk on top of the stablecoin's own. A yield is never free.
A stablecoin is a crypto token engineered to stay at a fixed value, almost always one US dollar. It lets people hold and move dollars on a blockchain without touching a bank directly, so a dollar can settle across the world in minutes at any hour.