Stablecoins: Crypto's Dollars

What Is a Stablecoin?

Most cryptocurrencies move dramatically in price — that is part of what attracts traders and what scares away everyone else. A stablecoin is a different kind of token, engineered from the start to stay anchored to a stable reference value. That reference is almost always one US dollar, though some stablecoins target the euro, the British pound, or other currencies.

Think of a stablecoin as a digital poker chip that is always supposed to be worth exactly one dollar. The chip travels freely across crypto markets, blockchains, and exchanges, while the dollar value it represents is meant to stay constant. Understanding how that peg is maintained — and what happens when it breaks — is the whole story.

Why Stablecoins Exist

Traditional bank accounts operate on business hours and clear payments over days. Crypto networks run continuously. Stablecoins bridge that gap by letting users hold and move something that behaves like a dollar but settles on a blockchain in minutes, any time of day or night.

They serve three main practical roles in crypto markets:

• Trading pairs. On crypto exchanges, stablecoins act as the dollar side of a trade. Instead of buying Bitcoin with bank dollars, a trader buys it with a stablecoin. This keeps the whole transaction on-chain and fast.
• Parking between trades. When someone wants to exit a volatile position without cashing out entirely, they can swap into a stablecoin and wait. The value is preserved in dollar terms without leaving the crypto ecosystem.
• DeFi activity. In decentralized finance, stablecoins are the primary unit for lending, borrowing, and providing liquidity. Protocols quote interest rates, collateral requirements, and fees in stablecoin terms.

Fiat-Backed Stablecoins: The Reserve Model

The most straightforward approach is simple: a company collects one real dollar (or dollar-equivalent) for every token it issues. These are called fiat-backed or reserve-backed stablecoins. The idea is that if every holder wanted to redeem at once, the reserves would cover it — exactly like a bank run test.

In practice, those reserves are usually held as a mix of cash and short-term government securities, particularly US Treasury bills. Treasury bills are short-dated government debt that matures in weeks or months, making them highly liquid — meaning they can be converted to cash quickly without losing much value. Reserve transparency matters enormously here: issuers publish regular attestations (independent reports confirming the reserves exist) or, in some jurisdictions, face regulatory audits.

Fiat-backed stablecoins are the dominant type by volume. Their main weakness is that they require trust in a centralized issuer. If the issuer holds insufficient reserves, mismanages funds, or faces regulatory action, the peg is at risk. Users cannot verify the reserves in real time just by reading the blockchain — they must rely on external reporting.

Crypto-Collateralized Stablecoins

A second approach replaces the dollar reserves with cryptocurrency collateral, typically a well-known asset like Ether. Because crypto prices are volatile, these systems require overcollateralization — meaning the collateral held is worth more than the stablecoins issued. Suppose a protocol requires $150 worth of Ether to mint $100 worth of stablecoins; the extra cushion absorbs price swings without breaking the peg.

Smart contracts — self-executing programs on the blockchain — handle the collateral automatically. If the collateral value falls too far, the contract liquidates (sells off) the position before it can become undercollateralized. This process is transparent and auditable on the blockchain, which is an advantage over the fiat model. The trade-off is complexity and vulnerability to sharp, sudden price drops that outrun the liquidation mechanism.

Algorithmic Stablecoins and the Terra Collapse

A third category, algorithmic stablecoins, attempts to maintain the peg through software-driven supply adjustments rather than holding any meaningful reserves. In theory, the algorithm expands the token supply when the price rises above one dollar (reducing scarcity, pushing the price back down) and contracts supply when it falls below (increasing scarcity, pushing the price back up).

The most widely studied failure of this model was Terra (LUNA) in May 2022. Terra's stablecoin, UST, used a dual-token system: holders could always exchange one UST for one dollar's worth of the companion token LUNA, and vice versa. This arbitrage mechanism was supposed to keep UST at exactly $1.00. When confidence broke and large holders began redeeming UST, the system minted enormous amounts of LUNA to cover redemptions. That flooded the market with LUNA, collapsing its price, which destroyed confidence in UST further, which triggered more redemptions — a self-reinforcing spiral economists call a "death spiral." Both tokens lost nearly all their value within days. Tens of billions of dollars in market capitalization were erased.

The Terra collapse is now the standard cautionary reference for algorithmic stablecoin design. It illustrated that a peg held only by market confidence and algorithmic rules — with no hard asset backing — can unravel faster than any mechanism can correct it.

The key question regulators and researchers now ask of any stablecoin: What happens if everyone tries to redeem at once? Fiat-backed tokens have an answer rooted in actual assets. Algorithmic designs often do not.

The Depeg: The Risk That Matters

A depeg is when the stablecoin's market price moves away from its one-dollar target — above it, below it, or catastrophically away from it. Depegs come in degrees. A minor depeg might mean the token briefly trades at $0.998 or $1.002 during a period of stress; arbitrageurs (traders who profit from small price differences) typically close these gaps quickly.

A severe depeg is something else entirely. If confidence collapses or reserves are exposed as inadequate, the token can trade well below $1.00 with no clear floor. Holders who cannot redeem directly through the issuer — ordinary users on secondary markets — may be left selling at a significant loss.

Traders and analysts who follow stablecoins typically watch several signals for peg health:

• Secondary market price — what the stablecoin actually trades for on exchanges, moment to moment.
• Reserve reports — the issuer's published breakdowns of what backs each token and how liquid those assets are.
• Redemption volume — a sudden surge in users converting stablecoins back to dollars can signal declining confidence.
• On-chain flows — large movements of stablecoins between wallets or off exchanges are visible on the blockchain and often precede stress events.

Reserve Transparency: The Watched Question

Because fiat-backed stablecoins are the dominant type, the quality and frequency of their reserve disclosures has become a central concern for markets and regulators alike. An attestation is a report from an accounting firm confirming that reserves exist as claimed at a specific point in time — it is not the same as a full audit, which examines the entire financial operation in depth.

Some issuers publish monthly or even daily attestations. Others have historically been opaque. Regulators in the United States, European Union, and elsewhere are actively developing frameworks that would require stablecoin issuers to hold specific types of assets, maintain minimum reserve ratios, and submit to regular audits. This regulatory environment is evolving quickly and affects how different stablecoins operate and where they can be used.

For context on how these assets move through broader markets and what drives the dollar they are pegged to, see the guides on what moves exchange rates and crypto market cycles. For the mechanics of how percentage price moves are reported, reading percentage moves is a useful companion.