Stablecoins Explained: What They Are, How They Work, and Where They Break

The most used product in crypto is not Bitcoin, an NFT, or a meme coin. It is the digital dollar. Stablecoins — tokens designed to hold a fixed value, almost always one US dollar — quietly settle more day-to-day activity than any other crypto asset, with a combined supply above $300 billion as of 2026. They are the bridge between volatile crypto markets and the money people actually think in. But “stable” is a design goal, not a guarantee, and the differences between how stablecoins maintain their value are exactly where the risk hides.

What a stablecoin actually is

A stablecoin is a crypto token whose issuer or mechanism promises it can always be exchanged for a fixed amount of a reference asset — typically one dollar. It moves like any other token: on a public blockchain, around the clock, across borders, settling in seconds or minutes. The point is to combine the rails of crypto with the price stability of ordinary money. The critical question for any stablecoin is simple: what exactly backs the promise? There are three main answers, and they are not equally solid.

Fiat-backed: dollars in a bank account

The dominant model. The issuer holds reserves — cash and short-term US Treasury bills — and mints one token for every dollar held. Redeem a token, and the issuer destroys it and wires you a dollar. Tether (USDT) and USD Coin (USDC) work this way and together account for the vast majority of the market.

The strength of this model is simplicity. Its weakness is trust in the issuer: you must believe the reserves exist, are liquid, and are reachable. That trust has been tested. Tether paid fines in 2021 over past misstatements about its reserves and has since published regular attestations. USDC briefly traded below $1 in March 2023 when part of its reserves was stuck in the collapsing Silicon Valley Bank — a reminder that even a well-run stablecoin inherits the risks of the banking system it sits on. Regulation is now catching up: the US GENIUS Act of 2025 requires payment stablecoin issuers to hold one-to-one reserves in cash or short-term Treasurys and disclose them monthly, and Europe’s MiCA imposes similar discipline.

Crypto-collateralized: backed by more than it issues

The second model backs the stablecoin with other crypto assets locked in smart contracts, visible on-chain to anyone. Because that collateral (say, ether) is volatile, the system demands overcollateralization — for example, $150 or more locked for every $100 of stablecoin issued — and automatically liquidates positions when collateral falls too far. DAI, and its successor USDS, are the longest-running examples.

The appeal is transparency and less dependence on banks: the backing is auditable in real time by anyone. The trade-offs are capital inefficiency and mechanism risk — in a violent market crash, liquidations can cascade faster than the system can process them, a stress DAI survived in March 2020 only with emergency intervention by its community.

Algorithmic: the model that failed spectacularly

The third model tried to hold the peg with no full backing at all, using algorithmic incentives and a sister token to absorb volatility. Its defining case is TerraUSD (UST). UST held its dollar peg through an arbitrage loop with the LUNA token, and grew to the third-largest stablecoin partly by offering near-20% yields on deposits. In May 2022, large redemptions broke the loop: UST slipped from its peg, the mechanism minted oceans of LUNA to defend it, LUNA’s price collapsed, and the “stablecoin” entered a death spiral. Roughly $40 billion of value evaporated in days, retail savers worldwide were wiped out, and founder Do Kwon was later arrested and extradited to face fraud charges.

Terra was not an isolated glitch; earlier algorithmic designs had failed the same way at smaller scale. The honest lesson: a stablecoin backed mainly by confidence in its own mechanism is stable until, suddenly, it is not. Regulators in both the EU and US have since effectively pushed unbacked algorithmic stablecoins out of the regulated market.

What stablecoins are actually used for

Beyond trading, stablecoins have found genuinely practical uses:

• A parking spot in volatile markets: traders move into stablecoins without exiting to a bank, which is why they dominate crypto trading volume.
• Cross-border transfers and remittances: a stablecoin moves internationally in minutes, any day, at any hour — often cheaper than wire transfers, though conversion costs at each end still matter.
• Dollar savings where dollars are scarce: in countries with high inflation or currency controls, stablecoins function as accessible digital dollars. This is a major driver of adoption across Latin America, Africa, and parts of Asia.
• Payments and payroll: freelancers and businesses increasingly invoice internationally in stablecoins to avoid slow correspondent banking.
• The base money of DeFi: lending, borrowing, and trading protocols quote and settle largely in stablecoins.

The risks, stated plainly

• Depeg risk: every model can trade below $1 under stress. With algorithmic designs it can be terminal; with backed designs it is usually brief but real.
• Issuer and reserve risk: a fiat-backed stablecoin is only as good as its reserves and the banks holding them.
• Freezing and censorship: major issuers can and do freeze tokens at specific addresses, usually at law enforcement request. Stablecoins are not censorship-resistant the way bitcoin is.
• No deposit insurance: a stablecoin balance is not a bank deposit. If the issuer fails, recovery depends on the legal regime, not a guarantee fund.
• Yield temptation: platforms offering high “interest” on stablecoins are lending them out at risk. Terra’s 20% yields were the bait before the collapse. Unusually high yield is a warning, not a feature.

The bottom line

Stablecoins are crypto’s most tangible success: hundreds of billions of digital dollars moving globally at internet speed, useful to people far beyond trading floors. But the word “stable” describes the goal, not a law of nature. Fiat-backed coins depend on trust in issuers and banks, crypto-collateralized coins on mechanisms surviving market storms, and algorithmic coins have already shown how badly the promise can fail. Know which kind you are holding, understand what backs it, and treat any stablecoin paying suspiciously high yield as the risk it actually is.

This content is for informational purposes only and does not constitute financial or investment advice.