Fiat-backed stablecoin
Fiat-backed stablecoins are issued by a central entity and backed one-to-one with fiat currency. For every token in circulation, the issuer holds an equivalent amount of dollars, or highly liquid, cash-equivalent assets, in reserve. The mechanics are straightforward: send $1 to the issuer and receive one stablecoin, return one stablecoin and receive $1 back, minus any fees. This redemption mechanism at a fixed $1 rate is what anchors the market price. If the token trades below $1, arbitrageurs can buy it cheaply and redeem it for a full dollar. If it trades above $1, they can mint new tokens for $1 and sell them at a premium. In both cases, activity nudges the price back toward the peg.
Tether () and Circle () are the two largest fiat-backed stablecoins. Tether, in particular, has expanded well beyond the dollar. The company now issues four fiat-pegged stablecoins (USD, EUR, CNH, and MXN) and even a gold-backed token. Its flagship USDT alone commands a of more than $167 billion, circulating across 18+ . According to its self-reported second-quarter 2025 figures, Tether holds $162 billion in assets against $157 billion in liabilities, leaving $5.4 billion in equity. With only 237 employees, that works out to roughly $23 million in equity per head. Quite the business model. Of those assets, a striking 74% are invested in US Treasury bills and overnight reverse repurchase agreements, effectively making Tether one of the largest private holders of short-term US government debt and earning billions in the process.
(Source: tether.io)
Nonetheless, Tether is incorporated in the British Virgin Islands and is not subject to direct US regulatory oversight. For years, it provided minimal disclosures, only beginning regular statements in 2021. An investigation the same year by the New York Attorney General (NYAG) revealed that Tether had not always been fully backed by cash, contrary to its claims at the time.
The lesson is clear: even fiat-backed stablecoins, while appearing stable on paper, are not risk-free. By design, they sacrifice for stability and capital efficiency. Their centralized structure concentrates risk in a single issuer. Key risks include:
- Transparency risk: Users must rely on the issuer’s attestations or third-party audits to confirm reserves truly back each token 1:1.
- Custodial risk: The banks or custodians holding reserves could fail, or funds could be mismanaged. For instance, USDC briefly traded as low as $0.88 in 2023 when Silicon Valley Bank collapse (USDC held $3.3 billion in reserve with SVB), showing how fiat-backed stables can be exposed to banking fragility.
- Credit risk of reserves: If reserves include credit instruments, those instruments could default or lose value.
- Operational risk: Failures, fraud, or mismanagement at the issuer itself could impair redemption and stability.
Crypto-collateralized stablecoins
Unlike fiat-backed tokens, crypto-collateralized stablecoins are backed by cryptocurrency reserves held directly . They are governed not by a central issuer, but by decentralized , that automatically enforce the rules. The leading example is USDS (formerly DAI), a decentralized stablecoin launched in 2017. In this model, users lock up as and mint stablecoins against that collateral in a vault. Because crypto assets are highly volatile, these systems require over-collateralization. For instance, a user might deposit $1,500 worth of to mint 1,000 USDS (worth $1,000). The 150% collateral ratio ensures a buffer against price swings.
If the value of the collateral falls close to the loan value, the protocol automatically triggers liquidation. The collateral is seized by the smart contract and sold at a discount via Dutch auction to the highest bidder. Importantly, bidders must use USDS to purchase the discounted collateral, and that USDS is then burned by the protocol to cancel out the borrower’s outstanding debt. This process ensures that the system remains fully collateralized at all times. For the borrower, liquidation means they keep the USDS they minted but lose part, or all, of their collateral, depending on the shortfall.
This system also creates natural arbitrage opportunities whenever USDS drifts away from its $1 peg. If USDS trades above $1 (say, at $1.02), users can open new vaults, mint fresh USDS at roughly $1 cost, and sell it on the market for a profit. The increase in supply pushes the market price back down toward $1. Conversely, if USDS trades below $1 (say, at $0.98), buyers can scoop it up cheaply and use it to repay their vault debt. By retiring their liabilities at a discount, they save money, while the reduction in circulating USDS helps lift the price back toward the peg.
There are many variations and refinements across protocols, but the fundamental trade-offs remain the same: decentralization, capital efficiency, and risk. Crypto-collateralized stablecoins lean heavily toward decentralization, transparency, and censorship-resistance. With no central issuer to freeze tokens, they embody crypto’s ethos of trustless finance. The trade-off, however, is capital inefficiency, vast amounts of collateral sit idle, and exposure to several inherent risks:
- Governance risk: Protocol decisions, such as collateral types, ratios, and parameters, depend on token-holder governance, which can be slow, politicized, or captured by large players.
- Market volatility: If collateral prices crash too quickly, liquidations may not happen fast enough to cover all liabilities, creating a shortfall.
- Smart contract risk: Vulnerabilities in the code could be exploited, draining reserves or disabling liquidations.
- Contagion risk: Because USDS accepts other stablecoins as collateral, it inherits their vulnerabilities. Heavy reliance on a single stablecoin, such as DAI’s past exposure to USDC, creates systemic risk: if that collateral de-pegs or is frozen, the crypto-collateralized stablecoin could also lose its peg. At one point, USDC made up about 60% of DAI’s collateral base; today, that share has fallen to roughly 17%, reducing but not eliminating the risk.
Algorithmic and other stablecoins
Algorithmic stablecoins are an attempt to maintain a peg without direct collateral, using only algorithms and market incentives. Instead of holding reserve assets, these protocols dynamically adjust the stablecoin’s supply (or use a dual-token mechanism) to keep the price at $1. The idea is to create a fully decentralized and capital-efficient stablecoin, but in practice, algorithmic stablecoins have been extremely unstable. They rely on market confidence and arbitrage activity to function, and have historically been prone to “” in adverse conditions.
The most notable example of this is TerraUSD (UST), with its dual token model and rebasing model. Terra kept its stablecoin UST pegged to $1 through a “mint-and-burn” system tied to its sister token, LUNA. At any time, $1 worth of LUNA could be burned (removed from circulation) to mint 1 UST, or 1 UST could be burned to mint $1 worth of LUNA. This created a simple arbitrage loop: if UST traded above $1, traders minted it cheaply and sold it for profit, expanding supply and pushing the price back down. If UST traded below $1, traders bought it at a discount and redeemed it for $1 of LUNA, reducing supply and lifting the price. In theory, this kept UST stable, but in practice it depended entirely on confidence in LUNA. Once LUNA’s price collapsed, the mechanism failed and UST lost its peg.
Other algorithmic-inspired designs are emerging. One example is Ethena’s USDe, a hybrid model that uses a delta-neutral hedging strategy. Users deposit ETH, and Ethena simultaneously shorts an equivalent amount of ETH perpetual futures on . The long spot plus short perps combination cancels out ETH’s price exposure, leaving a synthetic dollar position. The stability of USDe, however, depends on deep in perpetual markets, the behavior of , and Ethena’s ability to actively manage its hedges.
Algorithmic stablecoins sacrifice collateral backing for decentralization and capital efficiency, but greatly increase stability risk. They require constant market confidence and sufficient demand to support the peg. Key risks include:
- Confidence & reflexivity risk: Pure algorithmic stables depend entirely on belief in their peg. Once confidence erodes, redemptions can trigger a self-reinforcing “death spiral,” as seen with UST in 2022.
- Market liquidity risk: Peg stability relies on deep, continuous trading activity. If liquidity dries up on DEXs or CEXs, arbitrage can’t function properly and the stablecoin can deviate further from $1.
- Funding rate & hedge risk: Synthetic designs like USDe hedge crypto collateral with short perps. Sustained negative funding rates or exchange outages can make the hedge unprofitable or fail, endangering stability.
- Smart contract & vulnerabilities: Exploits in the code or manipulated price feeds can cause mispriced liquidations or excess minting, quickly destabilizing the system.
Fiat-backed stablecoins offer ease of use and typically deliver robust stability thanks to full fiat reserves, but they carry issuer credit risk and regulatory exposure. Crypto-collateralized stablecoins provide a decentralized alternative, appealing to those who want to minimize centralized counterparty risk. Their transparency and over-collateralization make sudden collapse less likely, so long as collateral values hold up. Yet they remain tethered to the volatility of crypto markets. Algorithmic stablecoins, meanwhile, are still experimental and fraught with failure risk. So where has the market placed its trust? Let’s take a closer look.
(Source: Token Terminal)
By 2025, the stablecoin market has grown to roughly $262 billion. Fiat-backed stablecoins still dominate, representing about 92% of (~$241 billion). Crypto-collateralized stablecoins account for around 3.3%, while algorithmic and hybrid models make up roughly 4.9%.
However, the growth dynamics tell a different story. Over the past year, algorithmic stablecoins have expanded nearly threefold, led largely by the rise of Ethena’s stablecoin, which is rapidly gaining traction. By comparison, fiat-backed stablecoins grew by about 59% in the same period.
The takeaway: while fiat-backed assets remain the bulk of the market due to their simplicity and regulatory familiarity, decentralized alternatives are scaling faster. As the GENIUS Act brings long-awaited regulatory clarity to stablecoin issuers, it raises key questions: will fiat-backed tokens retain their dominance, or are we witnessing the early stages of a broader shift toward algorithmic and crypto-collateralized models?
(Source: Token Terminal)
The GENIUS Act: a federal framework for stablecoins
Passed in July 2025, the Guiding and Establishing National Innovation for U.S. Stablecoins (GENIUS) Act marks the first comprehensive federal framework for dollar-pegged stablecoins. Under the law, only licensed entities can operate in the US, and every token must be backed 1:1 by cash or short-term US Treasuries. A ban on rehypothecation ensures that those reserves cannot be reused as collateral elsewhere, directly addressing long-standing solvency concerns.
Transparency is another core pillar. Issuers are required to provide regular, audited disclosures of their reserves. The Act also introduces robust consumer protections: reserves must be legally segregated from an issuer’s own assets, and in the event of insolvency, stablecoin holders have super-priority claims, meaning they are repaid before any other creditors.
(Source: Token Terminal)
Tether (USDT), which still dominates the market with roughly 70% of fiat-backed stablecoin supply, will face new pressures under this framework. Its reserves have historically included a mix of cash, Bitcoin, gold, and other less liquid assets, a composition that contrasts with the Act’s strict requirement for 1:1 backing with cash or short-term Treasuries. In addition, USDT issuers must now provide independent, detailed reserve attestations and comply with rules, as well as keep customer assets legally separate from their own funds. These transparency and governance obligations are notable given the company’s past controversies around reserve disclosures.
By contrast, USDC, issued by US-regulated entity Circle, already adheres more closely to the new standards. That positioning could allow it to capture a larger slice of the market.
Importantly, the GENIUS Act only covers fiat-backed payment stablecoins. Alternatives like crypto-collateralized and algorithmic stablecoins remain outside this federal framework for now, meaning their growth (as seen with projects like Ethena) will continue in a parallel, less regulated lane. How these two branches of the market evolve, and whether regulators eventually bring them under the same umbrella, will be one of the most important dynamics to watch in the coming years.
Globally, regulators are drawing similar boundaries: Europe’s new regime and Singapore’s stablecoin framework both focus tightly on fiat-backed tokens, Hong Kong is preparing to license dollar-pegged issuers by 2026, and Bahrain has explicitly banned algorithmic stablecoins. The direction of travel is clear: governments are embracing reserve-backed models while leaving decentralized and experimental designs at the edges of the system.
Conclusion
Three years after the UST collapse, the stablecoin market is both bigger and more diverse, but its core trade-offs remain clear. Fiat-backed stablecoins still dominate, accounting for more than 90% of supply, acting as the primary rails for trading, payments, and remittances, though their stability ultimately rests on reserve transparency and regulatory oversight. Crypto-collateralized models like USDS have proven that decentralization can work, but they remain constrained by over-collateralization and, in many cases, reliance on fiat-linked assets. Meanwhile, synthetic and hedged designs such as USDe push toward greater capital efficiency, but carry new risks tied to derivatives markets and centralized exchange infrastructure.
The key takeaway: stability comes from different sources. Fiat reserves (trust in issuers and regulators), crypto collateral (trust in transparent, over-collateralized systems), or algorithms and hedges (trust in market incentives and liquidity). Investors should be mindful of these differing risks and trade-offs when deciding which type of stablecoin to hold or use.
With the GENIUS Act in the US and Europe’s MiCA framework, regulation is now becoming the defining force in the sector. That clarity may cement the dominance of regulated fiat-backed players while leaving decentralized and algorithmic alternatives to evolve on the edges of the financial system, at least for now.
