What Is a Stablecoin? Fiat, Crypto, and Algorithmic Designs
A stablecoin is a cryptocurrency designed to keep a steady value, often pegged to the US dollar. Learn how fiat-backed, crypto-backed, and algorithmic types work and their risks.
In this article9 sections
Key points
- A stablecoin is a cryptocurrency designed to maintain a stable value, usually pegged to a fiat currency like the US dollar.
- Fiat-backed stablecoins hold reserves in traditional assets, crypto-backed ones use overcollateralized crypto, and algorithmic ones rely on code and market incentives.
- Each design carries risks: reserve transparency, liquidation cascades, and death spirals are common concerns.
What Is a Stablecoin?
A stablecoin is a type of cryptocurrency designed to keep a steady value. Most aim to track the US dollar, though some target other currencies or assets. Unlike Bitcoin or Ether, whose prices can swing wildly, a stablecoin tries to stay at $1.00. This makes it useful for trading, payments, and holding value without leaving the crypto ecosystem.
But “stable” does not mean risk-free. Stablecoins come in three main designs—fiat-backed, crypto-backed and algorithmic—each with its own way of holding the peg and its own failure modes.
How Stablecoins Keep Their Peg
All stablecoins use some mechanism to keep their price near the target. The mechanism usually falls into one of three categories.
Fiat-Backed Stablecoins
Fiat-backed stablecoins are the most common. A company holds reserves in traditional assets—like US dollars in a bank account, Treasury bills, or other cash equivalents—and issues digital tokens that represent a claim on those reserves. For every token in circulation, the issuer claims to hold one dollar (or equivalent) in reserve.
Examples include Tether (USDT) and USD Coin (USDC). These coins are typically centralized: a company manages the reserves, issues new tokens, and redeems them for dollars.
How it works: If you want to buy a fiat-backed stablecoin, you send dollars to the issuer (or an authorized partner). The issuer holds the dollars and gives you tokens. When you want your dollars back, you return the tokens and receive dollars. The peg holds as long as the issuer has enough reserves and honors redemptions.
Risks: The main risk is counterparty risk—trusting the issuer to actually hold the reserves. If the reserves are not there, or if the issuer faces a bank run, the stablecoin can lose its peg. Regulatory actions can also freeze or seize reserves. Transparency varies: some issuers publish regular attestations, but these are not the same as full audits.
Crypto-Backed Stablecoins
Crypto-backed stablecoins are backed by other cryptocurrencies, not fiat. Because crypto prices are volatile, these stablecoins are usually overcollateralized: you lock up more value in crypto than the stablecoins you receive. For example, you might deposit $150 worth of Ether to mint $100 worth of a stablecoin.
DAI, created by MakerDAO, is the best-known example (MakerDAO renamed itself Sky in 2024 and also issues a newer version called USDS). It is decentralized: smart contracts manage the collateral and the peg, and no single company holds dollars in a bank.
How it works: You deposit crypto into a smart contract (a vault). The contract lets you mint stablecoins against it. If the value of your collateral falls too low, the contract liquidates it to cover the debt. Stability fees and liquidation penalties help keep the system solvent.
Risks: Crypto-backed stablecoins face liquidation cascades. If the collateral price drops quickly, many vaults can be liquidated at once, causing further price drops. Smart contract bugs, oracle failures (oracles feed price data), and governance attacks are also risks. If the collateral crashes faster than liquidations can happen, the stablecoin can become undercollateralized and lose its peg.
Algorithmic Stablecoins
Algorithmic stablecoins use code and market incentives to maintain the peg, rather than holding large reserves. They often involve a second token that absorbs volatility. When the stablecoin’s price falls below $1, the protocol might incentivize users to buy it by offering the second token at a discount. When the price rises above $1, the protocol might mint and sell more stablecoins to push it down.
Some algorithmic stablecoins are partially collateralized, while others are purely algorithmic. TerraUSD (UST) was a well-known purely algorithmic stablecoin that collapsed in May 2022, wiping out billions in value. That event highlighted how fragile these designs can be when confidence breaks.
How it works: The protocol uses arbitrage opportunities to keep the price near $1. Traders can profit by minting or burning tokens when the price deviates. The system relies on continuous demand and trust.
Risks: Algorithmic stablecoins are the most experimental and risky. If the peg breaks and confidence falls, a “death spiral” can occur: the price drops, users rush to exit, the secondary token collapses, and the mechanism fails. There is no hard collateral to fall back on.
Comparing the Three Types
| Type | Backing | Example | Main Risk |
|---|---|---|---|
| Fiat-backed | Bank deposits, T-bills | USDT, USDC | Issuer default, reserve transparency |
| Crypto-backed | Overcollateralized crypto | DAI | Liquidation cascades, smart contract bugs |
| Algorithmic | Code and incentives | UST (failed) | Death spiral, loss of confidence |
The largest stablecoins right now
| Stablecoin | Type | Tokens in circulation | Where the issuer reports reserves |
|---|---|---|---|
| Tether (USDT) | Fiat-backed | 175,398,004,600 | Tether transparency page (quarterly attestations) |
| USD Coin (USDC) | Fiat-backed | 69,062,427,420 | Circle transparency page (monthly attestations) |
Circulation figures are live market data (14 Nov 2026, 00:11 UTC). Because each token is meant to be worth $1, the token count is roughly the dollar value of reserves the issuer says it holds. An attestation is an accountant’s check of reserves at a point in time; it is narrower than a full audit.
When pegs broke: two real cases
- TerraUSD (UST), May 2022: an algorithmic design. When holders rushed to redeem, the system minted ever more of its sister token LUNA, both collapsed within days, and UST never returned to $1.
- USD Coin (USDC), March 2023: a fiat-backed design. Circle disclosed that $3.3 billion of its roughly $40 billion in reserves sat at the failed Silicon Valley Bank. USDC fell to about $0.88 over a weekend and returned to $1 once US authorities guaranteed the bank’s deposits.
The lesson differs by type: UST failed because nothing outside the system backed it; USDC wobbled because a real reserve asset was briefly out of reach.
Rules that now apply
- European Union: the stablecoin parts of the Markets in Crypto-Assets regulation (MiCA) have applied since 30 June 2024. Issuers of euro or dollar tokens offered in the EU need authorisation and must hold reserves that can be redeemed at par.
- United States: the GENIUS Act, a federal law for payment stablecoins, was signed on 18 July 2025 (Public Law 119-27). It requires one-to-one reserves in cash and short-term Treasuries and monthly public reserve reports, and it takes effect by 18 January 2027 at the latest, or earlier once regulators finish its rules.
Ongoing coverage of issuers and regulators is on our stablecoin news page.
Practical Steps for Using Stablecoins
If you decide to use stablecoins, here are some practical steps to reduce risk.
- Understand the backing. Read the issuer’s documentation. For fiat-backed coins, check what assets back the token and how often reserves are attested. For crypto-backed, check the collateral ratio and liquidation rules. For algorithmic, understand the incentives and what happens if the peg breaks.
- Check the peg history. Look at how close the stablecoin has stayed to $1 over time. Brief deviations can happen, but frequent or large drops are a warning sign.
- Diversify. Do not put all your funds in one stablecoin. Different designs have different risks, so spreading across types can help.
- Use reputable platforms. When trading or holding stablecoins, use well-known exchanges and wallets. Avoid unknown platforms that promise high yields.
Common Mistakes and Risks
- Assuming all stablecoins are safe. The word “stable” refers to price stability, not safety. Each type has unique risks.
- Ignoring counterparty risk. Fiat-backed stablecoins depend on a company. If that company fails, you could lose money.
- Overlooking smart contract risk. Crypto-backed and algorithmic stablecoins rely on code. Bugs or exploits can drain funds.
- Chasing high yields. Some platforms offer high interest on stablecoin deposits (see where DeFi yield comes from). Those yields often come with hidden risks, like lending to risky borrowers or exposure to failing protocols.
- Forgetting about regulation. Some stablecoins are not authorised in every region; under MiCA, several exchanges limited non-compliant stablecoins for EU users.
Disclaimer: This article is for information only and is not investment, financial or trading advice. Cryptocurrency prices are highly volatile. Always do your own research.
