What Is a Stablecoin and How Does It Stay at $1?

Why do stablecoins exist?

Bitcoin’s price moving 5% before your coffee order finishes is the problem stablecoins solve. Crypto trading needs a neutral middle ground: an asset that behaves like cash but lives on the blockchain. That’s what a stablecoin is — a token that trades for one dollar, redeemable and transferable 24/7 without a bank account. On major exchanges, the deepest markets are USDT and USDC pairs, which is why almost every tutorial (including ours on buying your first crypto) routes through them.

The use cases reach past trading. A freelancer in Argentina or Turkey can hold dollar exposure without a US bank account. A remittance that costs 6% and three days through traditional rails clears in minutes for cents. And a trader who expects a volatile week can step into USDT between positions without withdrawing to a bank — exit and re-enter in seconds, not days.

How does a stablecoin stay at $1?

The three designs answer that question differently:

1. Fiat-backed. The issuer holds dollars and short-term US Treasuries equal to the coins in circulation and redeems $1 per token. USDT and USDC work this way. This is the dominant and most battle-tested model.
2. Crypto-backed. You lock up $150 of ETH in a smart contract to mint $100 of stablecoin. The over-collateralization absorbs price swings. More transparent — anyone can audit the vault on-chain — but more complex, and it can fail in a cascade if collateral crashes too fast.
3. Algorithmic. Coins expand and contract supply by formula, with no real reserves backing every coin. TerraUSD ran this design until May 2022, when it lost its peg and collapsed within days — taking roughly $40 billion of value with it.

The fiat-backed peg survives on one mechanism: redemption arbitrage. If USDT trades at $0.99, big players buy it at $0.99 and redeem it with the issuer for $1.00, pocketing the cent — and the buying pushes the price back to $1. The arbitrage only works while people trust the issuer will actually hand over the dollar. Trust is the entire machine.

How pegs actually break

Every depeg in crypto history has followed the same script, because a stablecoin is structurally a bank run waiting to see if it’s needed. Step one: a shock makes holders question the reserves — a banking partner fails, an audit reveals a gap, a market crash strains a crypto-backed vault. Step two: redemption requests spike. Step three: everyone else can see the redemption queue on-chain in real time, so fear outruns facts, and the market price breaks before redemptions can clear.

March 2023 is the clean case study: USDC’s issuer had $3.3 billion of reserves at Silicon Valley Bank, which failed on a Friday. USDC slid to roughly $0.87 by the weekend — not because reserves were gone, but because they were unreachable until Monday. When the dollar access was confirmed, the coin snapped back to $1 within days. Compare TerraUSD: same weekend-panic shape, but nothing behind the peg to snap back to. The lesson is that the quality and accessibility of reserves — not the promise — is the whole ballgame.

What are the risks?

“Stable” describes the goal, not a guarantee. The risk stack, from most to least likely: issuer risk — your money is a claim on a company, not cash in your pocket, and its reserves can be mismanaged; depeg risk — even fiat-backed coins trade a few cents off in panics; platform risk — a stablecoin is only as safe as wherever you hold it, and yields offered on “stable savings” products are compensation for lending risk, not a free lunch; regulatory risk — the rules are tightening as stablecoins grow systemic (the US passed its first federal stablecoin law, the GENIUS Act, in 2025, and issuers now operate under real licensing obligations rather than informal ones).

For beginners, the practical rules: stick to the largest, longest-established coins; never treat any stablecoin as a savings account; and if a platform offers you 20% APY on USDT, the yield isn’t coming from the stablecoin — it’s coming from you.

How to check a stablecoin’s health yourself

You don’t need to trust anyone’s marketing; the health indicators are public and take ten minutes to read:

• Redemption at par, in size. Has the issuer been paying large redemptions at exactly $1.00 through recent stress, or only small ones in calm markets? Redemption history is the only test that matters.
• Attestations, read carefully. Fiat-backed issuers publish monthly or quarterly reserve attestations. Read what an attestation actually says — usually “an accounting firm looked at documents on one day” — versus a full audit, which is stronger. Check what fraction of reserves is cash versus short-term Treasuries versus murkier instruments.
• Depeg history. How did the coin behave in the two or three worst market weeks of the past few years? Every stablecoin trades a few cents off in panics; what you’re looking for is whether it snapped back and how fast.
• Market cap stability. Steady or growing supply means money is comfortable sitting in it. Sustained outflows mean the sophisticated money is quietly leaving — usually before the headlines.

None of this makes a stablecoin safe; it makes your caution specific, which is the difference between a position you can defend and a hope you’re defending.