Introduction

Stablecoins are cryptocurrencies designed to hold a fixed value, typically one US dollar, by tying each token to a reserve asset or algorithmic mechanism. They combine the speed and programmability of blockchain with the price stability of traditional currency. And in 2026, they are far more than a crypto trading tool.

The stablecoin market now exceeds $300 billion in total capitalization. Transaction volume hit roughly $33 trillion in 2025, a 72% increase over the prior year. Visa and Mastercard settle transactions in stablecoins. Banks are building tokenized deposit products around them. Cross-border remittances, payroll, and treasury operations increasingly run on stablecoin rails.

Every stablecoin maintains its peg through a specific mechanism, and the mechanism defines the risk. There are three primary approaches: holding fiat reserves on a 1:1 basis, locking up overcollateralized crypto assets in smart contracts, or using algorithms to dynamically adjust token supply.

The Three Types of Stablecoins (and Why It Matters)

Not all stablecoins work the same way. The peg mechanism determines not just how a stablecoin keeps its price, but what happens when markets get volatile, when confidence wavers, or when a counterparty fails.

Fiat-backed stablecoins dominate the market. Crypto-collateralized stablecoins offer a decentralized alternative with higher complexity. Algorithmic stablecoins attempt stability without reserves, and most have failed. Each model carries distinct tradeoffs, and the differences matter whether you are a trader, a business accepting payments, or someone using stablecoins to access crypto-backed lending.

Fiat-Backed Stablecoins

Fiat-backed stablecoins are the simplest and most widely used. Tether (USDT) leads the market with roughly $180+ billion in circulation. Circle's USD Coin (USDC) is second at approximately $70+ billion. Together, they account for the vast majority of all stablecoin activity.

How Fiat Reserves Maintain the Peg

The concept is straightforward. For every stablecoin issued, the issuer holds one dollar (or equivalent liquid asset) in reserve. When you buy one USDC, Circle adds a dollar to its reserve. When you redeem one USDC, Circle returns a dollar and removes the token from circulation.

This mint-and-redeem mechanism creates the foundation of peg stability. But the real enforcement comes from arbitrage. If USDC trades at $0.98 on the open market, an arbitrageur can buy it at the discount and redeem it from Circle for $1.00, pocketing the difference. If it trades at $1.02, the arbitrageur can mint new USDC from Circle at par and sell it at the premium. This feedback loop constantly pulls the price back toward $1.

The SEC's April 2025 statement on stablecoins formally described this mechanism for what it called "Covered Stablecoins," recognizing that the issuer stands ready to mint and redeem at par in unlimited quantities.

What's Actually in the Reserves?

"Backed by dollars" does not always mean there's a pile of cash in a vault. In practice, reserves include a mix of highly liquid assets.

Circle holds USDC reserves in government money market funds managed by BlackRock and custodied at BNY Mellon. Tether's reserves consist primarily of short-term US Treasuries, reverse repurchase agreements, and cash equivalents. Both issuers publish regular attestations detailing their reserve composition.

The GENIUS Act, signed into law in July 2025, now requires US stablecoin issuers to maintain full 1:1 reserve backing with liquid assets such as US dollars, Treasury bills, and bonds. This codified what leading issuers were already doing and gave institutions greater confidence in the asset class.

Treasuries and money market funds are considered cash-equivalent, but they are not identical to cash. In a severe liquidity crunch, even short-term government securities could face temporary pricing dislocations. The reserves are high quality, but "fully backed" is not the same as "risk-free."

Key Risks of Fiat-Backed Stablecoins

The primary risks are counterparty exposure and run dynamics. Reserves are held by third-party custodians and financial institutions. If a custodian fails or freezes assets, the peg can break temporarily. This happened in March 2023 when USDC briefly de-pegged after $3.3 billion in Circle reserves were frozen at Silicon Valley Bank. The peg restored within days once the funds were made accessible, but the episode demonstrated that even well-managed fiat-backed stablecoins are not immune to systemic banking stress.

Transparency is another factor. Tether has faced years of scrutiny over its reserve disclosures and audit practices. While its attestations now show substantial Treasury holdings, the company's history of opacity remains a point of debate. For holders evaluating risk, the quality and verifiability of reserves matter as much as the headline "1:1 backed" claim.

The European Central Bank and other regulators have also flagged structural similarities between stablecoin redemptions and money market fund runs. A sudden spike in redemptions could force issuers to liquidate reserves rapidly, potentially at a loss, compounding downward pressure on the peg.

Crypto-Collateralized Stablecoins

Crypto-collateralized stablecoins take a different approach. Instead of holding dollars in a bank, they lock up digital assets in smart contracts and mint stablecoins against them. The most established example is DAI (now transitioning to USDS under the Sky protocol), with a market capitalization around $5.3 billion.

How Overcollateralization Works

A user deposits crypto, typically ETH or other approved tokens, into a smart contract on the blockchain. The system then allows them to mint stablecoins, but only up to a fraction of the collateral's value. For example, depositing $150 worth of ETH might allow minting $100 worth of DAI. That $50 buffer is the overcollateralization, and it exists to absorb price swings in the underlying collateral.

If the value of the deposited ETH drops below a set liquidation threshold, the smart contract automatically sells the collateral on the open market to repay the debt and protect the system's solvency. This is automated entirely without human intervention.

Arbitrage and Governance

Arbitrage maintains the peg here too, though the mechanics differ. If DAI trades below $1, holders can buy it at a discount and use it to repay outstanding loans at face value, effectively profiting from the price difference. If DAI trades above $1, users are incentivized to mint more DAI (which they receive at $1 par) and sell it on the market.

MakerDAO (now Sky) also uses governance levers to influence the peg. Stability fees (interest rates on minted DAI) and the Dai Savings Rate (yield paid to DAI holders who deposit into the savings contract) adjust supply and demand. The protocol also introduced a Peg Stability Module that allows direct swaps between DAI and other stablecoins, which significantly tightened peg stability over time.

DAI's collateral base has expanded beyond pure crypto. It now includes real-world assets and other stablecoins, which reduces dependence on volatile crypto prices but introduces new forms of counterparty risk.

Key Risks of Crypto-Collateralized Stablecoins

The biggest vulnerability is collateral volatility. A sharp, sudden crash in ETH prices can trigger cascading liquidations across the system. If the market moves faster than the liquidation mechanism can execute, the system may become undercollateralized.

Smart contract risk is also real. The entire system runs on code. A bug, exploit, or oracle failure (the price feeds that tell the smart contract what collateral is worth) could compromise the peg.

DAI's brief de-pegging in March 2023 illustrated concentration risk. A substantial portion of its collateral was tied to USDC, which itself was affected by the Silicon Valley Bank crisis. When USDC wobbled, DAI wobbled with it. Diversified collateral helps, but hidden correlations can still surface during market stress.

Algorithmic Stablecoins

Algorithmic stablecoins attempt to maintain their peg without holding any reserves at all. Instead, they rely on smart contracts that expand or contract the token supply based on price.

How Algorithms Attempt to Maintain the Peg

The basic logic is when the stablecoin trades above $1, the protocol mints new tokens, increasing supply and pushing the price down. When it trades below $1, the protocol burns tokens (or incentivizes users to burn them), reducing supply and pushing the price up.

Some models use a dual-token system. One token is the stablecoin itself; the other is a volatile "share" token that absorbs price fluctuations. Users swap between the two based on incentives built into the protocol.

It theory, it should create a self-correcting system that doesn't need external assets. In practice, it has repeatedly failed.

Why Most Algorithmic Stablecoins Have Failed

The most consequential failure was Terra/UST in May 2022. UST was the largest algorithmic stablecoin, exceeding $18 billion in market capitalization. It maintained its peg through a mint-burn relationship with a companion token called LUNA. When confidence cracked, the system entered a death spiral: UST holders rushed to redeem, LUNA supply exploded, both tokens collapsed, and over $40 billion in combined value vanished within days.

The fundamental problem is that algorithmic stability depends entirely on market confidence and continued demand. There is no hard asset floor. When trust erodes, there is nothing to stop the fall, and the same incentive mechanisms designed to restore the peg can accelerate the collapse instead.

Post-Terra, regulators have taken a dim view. The EU's MiCA framework treats algorithmic stablecoins as potential systemic threats. The US GENIUS Act effectively requires full collateralization for regulated issuers, which sidelines the pure algorithmic model from the regulated market.

Hybrid Models

Not all non-fiat models are purely algorithmic. Ethena's USDe, which has grown to over $6 billion in market cap, uses a delta-neutral hedging strategy: holding crypto spot positions and simultaneously shorting perpetual futures to offset price exposure. This isn't traditional collateralization or algorithmic supply adjustment. It's a derivatives-based approach that carries its own risks, particularly around funding rate fluctuations and counterparty exposure in futures markets.

Frax, once a hybrid algorithmic/collateralized model, moved to full collateralization after the Terra collapse. The market has broadly signaled that partial or zero-reserve approaches do not inspire enough confidence to sustain a peg at scale.

The Role of Arbitrage in Maintaining Any Stablecoin Peg

Arbitrage deserves standalone attention because it is the universal enforcement mechanism across all stablecoin types.

No matter how a stablecoin is designed, the peg ultimately holds because rational market participants profit from correcting price deviations. For fiat-backed coins, the arbitrage is direct: buy below $1, redeem at par. For crypto-collateralized coins, the incentive flows through loan mechanics: buy cheap DAI, repay $1 of debt. For algorithmic coins, the protocol itself offers the profit incentive, though this mechanism can break down when confidence disappears.

Market makers on centralized and decentralized exchanges also play a stabilizing role, continuously quoting prices near $1 and absorbing small fluctuations. Deep liquidity makes price deviations smaller and shorter-lived. Thin liquidity makes them worse.

This is why market size and adoption matter for peg stability. The larger and more liquid a stablecoin becomes, the more arbitrageurs and market makers participate, and the tighter the peg tends to be.

What Happens When a Stablecoin Loses Its Peg?

De-pegging occurs when a stablecoin's market price diverges significantly from its target value.

The causes vary: reserve insufficiency, loss of market confidence, counterparty failures, liquidity crises, or smart contract vulnerabilities. Sometimes it is a combination. The SVB-related USDC de-peg in March 2023 was driven by counterparty risk and resolved quickly once the banking situation stabilized. The Terra/UST collapse in 2022 was driven by a fundamental design failure and was permanent.

The structural risk, as flagged by both the ECB and the Federal Reserve, is that stablecoin redemptions can behave like bank runs. A surge in redemptions forces issuers to liquidate reserves rapidly. If the reserves include anything less liquid than cash, forced selling can depress prices, making the reserve shortfall worse and triggering more redemptions. This contagion dynamic is why reserve quality and liquidity matter so much.

Regulation Is Reshaping Stablecoin Stability

Regulatory clarity has become a material factor in stablecoin peg confidence. Institutions are far more willing to adopt stablecoins when reserve rules, disclosure requirements, and supervisory expectations are clearly defined.

The most significant development is the US GENIUS Act, signed in July 2025. It established the first comprehensive federal framework for stablecoin issuers, requiring full 1:1 reserve backing with liquid assets, regular public disclosure, and formal authorization standards. US Treasury Secretary Scott Bessent stated that stablecoins would strengthen the dollar's global reserve status and increase demand for US Treasuries.

Europe's MiCAR framework, in effect since 2024, regulates stablecoin issuance within the EU and explicitly prohibits yield-bearing stablecoins from regulated issuers. Hong Kong introduced its own stablecoin regulation in August 2025. Japan approved its first yen-pegged stablecoin later that year. On the other end of the spectrum, China has banned stablecoins outright as of early 2026.

The net effect of this regulatory wave is that fiat-backed, fully reserved stablecoins are gaining institutional legitimacy while under-collateralized and algorithmic models are being pushed to the margins. For users, regulatory status is now a meaningful signal of peg reliability.

Stablecoins and Digital Asset Lending

Stablecoins serve as the base currency for most on-chain lending activity. As of August 2025, total stablecoin loan balances stood at $14.8 billion, with an average borrower APR around 6.4%.

Because stablecoins hold a stable value, they are the natural disbursement currency when borrowing against volatile crypto assets like Bitcoin or Ethereum. A borrower can lock up BTC as collateral, receive stablecoins (or fiat), and access liquidity without selling their holdings. Platforms like Arch offer Bitcoin and crypto-backed loans with disbursement in stablecoins or USD.

Conclusion

Stablecoins maintain their value through specific, identifiable mechanisms. Fiat-backed stablecoins hold liquid reserves and rely on direct redemption and arbitrage. Crypto-collateralized stablecoins use overcollateralization and smart contract enforcement. Algorithmic stablecoins attempt supply-adjustment without reserves, and the track record is poor.

The fiat-backed model dominates because it is the simplest, the most transparent, and the most compatible with regulatory frameworks now taking shape globally. As the stablecoin market matures past $320 billion, the quality and verifiability of reserves have become the primary differentiators.

Frequently Asked Questions

How do stablecoins keep their value at $1?

Through reserve backing (holding $1 in liquid assets for each token), overcollateralization with crypto assets, or algorithmic supply adjustments. The most common and reliable method is fiat reserves combined with a redemption mechanism and market arbitrage.

What happens if a stablecoin loses its peg?

De-pegging means the stablecoin's market price diverges from its target. This can be temporary (caused by liquidity crunches or counterparty issues, as with USDC during the SVB crisis) or permanent (caused by structural failure, as with Terra/UST in 2022).

Are stablecoins safe?

Safety depends on the mechanism and the issuer. Fiat-backed stablecoins with transparent reserves and regulatory compliance are generally considered lower risk. Algorithmic stablecoins have a poor track record. No stablecoin is entirely risk-free.

What are stablecoins backed by?

Fiat-backed stablecoins are typically backed by US dollars, short-term Treasury bills, and money market fund shares. Crypto-collateralized stablecoins are backed by digital assets like ETH. Algorithmic stablecoins may have no backing at all.

Do stablecoins pay interest?

Most major stablecoins (USDT, USDC) do not pay interest to holders. Issuers earn yield on reserves, but regulations currently prohibit most regulated issuers from passing that yield to holders directly. Yield-bearing stablecoins exist as a separate product category.

How is a stablecoin different from a CBDC?

Stablecoins are issued by private companies and backed by commercial reserves. Central bank digital currencies (CBDCs) are issued directly by a government's central bank. Both target price stability, but they differ in governance, issuance authority, and regulatory treatment.

About Arch

Arch is building a next-gen wealth management platform for individuals holding alternative assets. Our flagship product is the crypto-backed loan, which allows you to securely and affordably borrow against your crypto. We also offer access to bank-grade custody, trading and staking services.

Disclaimer: This article is for informational purposes only and does not constitute investment, legal, or tax advice. Cryptocurrency investments are volatile and risky. Always conduct your own research before making investment decisions.