Fiat-Backed Stablecoins Explained: How USDT and USDC Work

Fiat-backed stablecoins are cryptocurrencies that are designed to maintain a stable value by being backed or pegged to a fiat currency, such as the US dollar or the euro. 

These stablecoins are typically backed by reserves of the corresponding fiat currency held by a centralized entity, such as a bank or a financial institution. 

The purpose of pegging the stablecoin to a fiat currency is to provide stability and reduce the price volatility often associated with other cryptocurrencies like Bitcoin or Ethereum.

As of early 2026, the total stablecoin market sits at roughly $315 billion, according to Binance Research data compiled from DeFiLlama. Fiat-backed stablecoins make up the overwhelming majority of that figure. Two coins, USDT and USDC, account for about 84% of total stablecoin market cap on their own.

How Do Fiat-Backed Stablecoins Work?

First things first, let’s clarify how these assets work.

There are several ways for stablecoins to maintain a stable peg. Those that are backed by fiat currencies rely on the financial reserves of the issuing company. 

In short, the process of issuing new coins looks as follows:

1. A user sends some fiat currency to the company’s bank account.
2. The company mints digital assets of the same value on the blockchain.
3. Then it sends this sum to the user’s crypto wallet.

Thus, the number of digital assets in circulation always equals the sum of money stored in the company’s vault. The real rate may slightly fluctuate. But it rarely exceeds 1-2%.

Could an issuer mint more coins than it holds in reserves? In theory, yes. In practice, the deterrents are regulatory pressure and public attestation schedules. Financial regulators in the U.S. and EU can require reporting, impose penalties, and restrict operations. Both major issuers now publish reserve attestations on a defined schedule. Those reports are not full independent audits, but they do provide a third-party check on reserve balances. The gap between attestation and full audit remains a legitimate concern for risk-conscious holders.

What Is Actually in the Reserves?

The phrase ‘backed by fiat’ understates what is actually happening. Modern fiat-backed stablecoins hold a mix of assets, not pure cash.

USDC holds cash in regulated U.S. banks and the Circle Reserve Fund, a 2a-7 money market fund managed by BlackRock. A 2a-7 fund is a highly regulated, low-risk vehicle that invests in short-term U.S. government securities and similar instruments. It is not the same as cash, but it is designed to maintain a stable $1 net asset value. Circle publishes the reserve balance weekly.

USDT holds primarily U.S. Treasury bills, cash, and other liquid instruments. As of Q1 2026, Tether reported a reserve buffer of $8.23B above its total liabilities, meaning it holds more assets than the value of all USDT in circulation. Tether publishes reserve breakdowns quarterly.

The distinction that matters: neither issuer is simply holding dollars in a bank vault. Both are holding short-duration, high-quality assets that can be liquidated quickly. The risk is not that reserves do not exist. The risk is that in a severe market dislocation, even high-quality short-term assets could face temporary liquidity constraints before redemptions are met.

USDT vs. USDC: Side-by-Side Comparison

Choosing between the two dominant fiat-backed stablecoins comes down to three things: reserve transparency, redemption access, and regulatory standing. Here is how they compare as of mid-2026.

👉 Quick takeaway: USDT leads on volume, liquidity depth, and DeFi penetration. USDC leads on transparency, attestation frequency, and regulatory positioning. For EU users or regulated institutions, USDC is the safer compliance choice. For high-volume trading and DeFi, USDT’s liquidity is unmatched.

If you are a retail user in the EU, neither USDT nor USDC is currently authorized as a MiCA-compliant e-money token for retail use. Euro-denominated alternatives are emerging through the Qivalis consortium, backed by major European banks including BBVA.

If you are trading on centralized exchanges outside the EU, USDT’s deeper liquidity makes it the default. If reserve transparency is your priority, USDC’s weekly attestations and BlackRock-managed reserve fund set a higher disclosure standard.

The Regulatory Divide: U.S. vs. EU in 2026

Where you use a fiat-backed stablecoin now determines which rules apply. The regulatory landscape split sharply in 2024 and 2025.

In the European Union, the Markets in Crypto-Assets regulation (MiCA) is fully in force. Stablecoins classified as asset-referenced tokens (ARTs) or e-money tokens (EMTs) must be authorized by an EU regulator before being marketed to retail users. ESMA and the European Commission published guidance in early 2025 making clear that non-MiCA-compliant ARTs and EMTs face restrictions on EU retail distribution. Neither USDT nor the U.S.-issued USDC currently holds MiCA authorization as an EMT for retail use in the EU.

That gap is pushing European banks to act. BBVA dropped its solo stablecoin project in early 2026 to join the Qivalis consortium, a group of major European banks building a euro-denominated stablecoin under MiCA rules. If you hold or use stablecoins in the EU, watch this space.

In the United States, the picture is less settled. The GENIUS Act, a proposed federal stablecoin framework, has been debated in Congress. It would require stablecoin issuers to hold 1:1 reserves in high-quality liquid assets and submit to federal or state oversight. No final law has passed at time of publication. Individual states continue to apply their own frameworks.

The practical implication: if you are in the EU, check whether your platform’s stablecoin is MiCA-compliant before treating it as a stable store of value for anything beyond short-term trading.

Risks of Fiat-Backed Stablecoins

Alright, so there are higher authorities that scrupulously monitor these companies and bring down the counterparty risk to the minimum. What would be the biggest pitfalls of using such currencies then?

First, there is a risk of censorship.

Bitcoin was invented in the first place to stand against the censorship of central banks that issue fiat money. Yet, fiat-backed stablecoins do exactly the opposite. For example, central parties standing behind these coins may block specific addresses on a whim. 

Circle froze Tornado Cash smart contract addresses totaling $437 million worth of USDC following the U.S. Treasury’s OFAC designation of Tornado Cash in August 2022. The freeze demonstrated that fiat-backed stablecoin issuers will comply with government sanctions orders, with no on-chain mechanism available to users to resist or appeal.

Dai of Maker DAO runs a similar censorship risks since the majority of its collateral is USDC.

A more recent case involves Tether that blacklisted $31 million worth of USDT following the alleged FTX hack.

Of course, the hackers that stole all those funds were up to no good. But be sure that law-abiding citizens have suffered from these actions together with the criminals.

Reserve transparency is real, but it is not equal across issuers.

Tether has a documented history of misrepresentation. Its earlier claim to be fully backed 1:1 by cash was revised after a CFTC settlement. Today, Tether publishes quarterly attestation reports rather than full audits. Its Q1 2026 report shows reserves weighted toward U.S. Treasuries and liquid assets, with an $8.23B buffer above total liabilities. That is meaningful progress. It is still not a full independent audit.

Circle goes further. USDC reserves are attested weekly by a Big Four firm under AICPA standards. The reserve fund is a 2a-7 money market fund managed by BlackRock, a structure that limits credit risk. You can verify the current reserve balance on Circle’s transparency page any day of the week.

The core opacity problem persists for smaller issuers with no public attestation schedule. For USDT and USDC specifically, the question in 2026 is not whether reserves exist but whether quarterly versus weekly attestation frequency is sufficient for your risk tolerance.

Finally, there are problems with redeeming stablecoins. 

Users may face problems when trying to convert such assets to cash and cash equivalents.

For example, Tether obliges its users to pay $150 for verification to be able to cash out their digital assets. Besides, the minimum size of the transaction equals $100,000. Such a sum can become a real obstacle for regular users.

Fiat-Backed Stablecoin List

At the time of writing, the full list of stablecoins includes a few dozen of assets. The number of the most popular options is much smaller, though. Let’s review the fiat-backed stablecoins with the highest market cap.

USDT

• Issuing organization: Tether
• Launched: 2014
• Circulating supply: ~$187B to $189.5B (May 2026)
• Reserve attestation: Quarterly, independent attestor
• Reserve buffer: $8.23B above total liabilities (Q1 2026)
• Reserve composition: Primarily U.S. Treasuries, cash, and liquid instruments

The Hong Kong-based company Tether issued its first stablecoin USDT in 2014. This is one of the first and the most reputable stablecoins that has lived through thick and thin.

Tether has become the first coin of its kind to combine the benefits of both cryptocurrencies and fiat. It has provided its users with the possibility to transfer value at a low cost in a fast and transparent manner. 

What about Tether USD coin’s compatibility? Initially launched on the Ethereum network, it has added the support of other blockchains over the following years. At the time of writing, it operates on Bitcoin, TRON, EOS, Algorand, and many other protocols.

Many rivals have emerged over the past few years. Yet, Tether’s market capitalization remains the highest.

USDC

• Issuing organization: Circle
• Launched: 2018
• Circulating supply: ~$78.1B (May 2026)
• Reserve attestation: Weekly, Big Four assurance under AICPA standards
• Reserve composition: Cash at regulated U.S. banks plus the Circle Reserve Fund, a 2a-7 money market fund managed by BlackRock

USD Coin, or shortly USDC, is another popular fiat-collateralized stablecoin with a peg to the US dollar. The Centre Consortium standing behind its creation was co-founded by a reputable cryptocurrency exchange Coinbase and a financial technology company Circle.

Just like Tether, it supports a number of different blockchains such as Ethereum, TRON, Binance Smart Chain, and Solana. However, unlike Tether, it has never been accused of any dirty games and has a spotless reputation.

FDUSD (First Digital USD)

• Issuing organization: First Digital Trust
• Launched: 2023
• Chains: Ethereum, BNB Chain

After Paxos halted BUSD minting in February 2023 following an NYDFS order, FDUSD emerged as the primary USD-pegged stablecoin on Binance. It is backed by cash and cash equivalents held in segregated accounts. Binance lists it as a zero-fee trading pair on its platform, which has driven rapid adoption. It is not yet subject to the same level of public attestation scrutiny as USDT or USDC, so treat it as a higher-counterparty-risk option for now.

How to Choose a Fiat-Backed Stablecoin

Four questions narrow the field fast.

1. Are you in the EU?

If yes, prioritize MiCA-compliant options. Neither USDT nor U.S.-issued USDC currently holds MiCA EMT authorization for retail use. Watch for euro-denominated alternatives emerging from the Qivalis consortium in 2026 and 2027.

2. Do you need direct redemption?

If you plan to redeem directly with the issuer rather than selling on an exchange, USDT charges a $150 verification fee and requires a $100,000 minimum transaction. USDC has a lower barrier through Circle accounts. For most retail users, exchange-based selling is the practical path.

3. How much does reserve transparency matter to you?

USC is attested weekly under AICPA standards by a Big Four firm. USDT is attested quarterly. If you are holding a large position and reserve quality is a concern, USDC’s disclosure frequency is meaningfully higher.

4. Where do you need liquidity?

USDT has the deepest liquidity across centralized and decentralized exchanges globally. Its circulating supply of roughly $187B to $189.5B dwarfs USDC’s $78B. For high-volume trading or DeFi strategies, USDT’s market depth is a practical advantage.

If none of the above constraints apply, USDT is the path of least friction for most active traders. If you prioritize regulatory cleanliness and reserve transparency, USDC is the stronger choice.

Frequently Asked Questions

How do fiat-backed stablecoins maintain their $1 peg during market stress?

The peg is maintained through arbitrage and direct redemption. If USDT trades below $1 on an exchange, large holders can buy it cheaply and redeem it with Tether for $1, pocketing the difference. That buying pressure pushes the price back up. In practice, USDT has briefly traded as low as $0.96 during extreme stress events but has always recovered. The mechanism works as long as reserves are liquid enough to meet redemption demand.

What is the difference between an attestation and a full audit?

An attestation is a limited-scope report where an independent accountant checks that reserve balances match reported figures at a specific point in time. A full audit examines internal controls, accounting practices, and financial statements over a period. Neither USDT nor USDC has undergone a full public audit. Both publish attestations on a defined schedule.

Are fiat-backed stablecoins safe to hold long-term?

For short-term use (trading, payments, transfers), the two major issuers have a strong track record. For long-term holding, the risks are censorship (issuers can freeze addresses), regulatory change (MiCA and U.S. frameworks are still evolving), and reserve quality (both issuers hold assets, not pure cash, which carry their own risks). The Atlanta Fed’s 2026 policy paper on fiat-backed stablecoins and narrow banking identifies reserve storage and consumer protection as the key systemic concerns.

Which fiat-backed stablecoins are MiCA-compliant in the EU?

As of mid-2026, neither USDT nor U.S.-issued USDC holds MiCA authorization as an e-money token for EU retail distribution. ESMA and the European Commission have published guidance restricting non-MiCA-compliant ARTs and EMTs. Euro-denominated MiCA-compliant alternatives are in development through the Qivalis consortium.

Bottom Line

Fiat-backed stablecoins are the backbone of the crypto economy. At $315B in total market cap, they are too large to ignore. USDT and USDC together cover 84% of that market.

The case for them is practical. They hold their peg. They are liquid. They work on dozens of blockchains. For trading, payments, and moving value across borders, they do the job.

The case against them is also practical. They are censorable. Issuers have frozen addresses at government request and will do so again. Direct redemption is not designed for retail users. Neither coin is currently MiCA-authorized for EU retail use.

If censorship resistance and full decentralization are your priorities, fiat-backed stablecoins are not the answer. Crypto-backed alternatives, including decentralized protocols like Liquid Loans, offer a different tradeoff: no centralized issuer to freeze your funds, no fiat reserve to audit, and no single point of regulatory pressure.

Learn more about USDL, the decentralized stablecoin on Base, here.