What Are Stablecoins? USDT, USDC, DAI and Beyond

A stablecoin is a cryptocurrency designed to maintain a stable value — usually pegged to the US dollar at a 1:1 ratio. While Bitcoin and Ethereum swing 5–10% in a day, a well-functioning stablecoin stays at $1.00 (give or take a fraction of a cent).

Stablecoins are the most used category of cryptocurrency by transaction volume. In 2025, stablecoins processed over $10 trillion in on-chain transactions — more than Visa’s annual volume. They’re the bridge between the volatile crypto world and the stable fiat world.

Why Stablecoins Exist

Three core use cases:

1. Trading pairs. Instead of converting to fiat when you sell Bitcoin (slow, expensive, requires bank), you sell BTC for USDT and keep your funds on-chain. Ready to buy back instantly.

2. DeFi backbone. Lending, borrowing, and yield farming all revolve around stablecoins. They’re the “dollars” of the decentralized financial system.

3. Payments and remittances. Sending $1,000 from the US to the Philippines costs $0.50 in stablecoin fees and arrives in minutes. Western Union charges $15–$50 and takes days.

Types of Stablecoins

Fiat-Backed (Centralized)

A company holds reserves (cash, bonds, Treasury bills) and issues tokens backed 1:1 by those reserves.

USDT (Tether)

• Largest stablecoin (~$115B+ market cap)
• Issued by Tether Limited
• Available on virtually every chain (Ethereum, Tron, Solana, etc.)
• Reserves: mix of US Treasuries, cash, commercial paper, secured loans
• Controversy: Tether has historically been reluctant to provide full, independent audits. They publish quarterly “attestations” but not full audits. Despite this, USDT has maintained its peg through multiple market crashes.

USDC (USD Coin)

• Second largest (~$35B+ market cap)
• Issued by Circle, regulated US company
• Reserves: US Treasuries and cash at regulated financial institutions
• Regular third-party attestations from Grant Thornton
• Briefly depegged to $0.87 in March 2023 when Silicon Valley Bank (which held some reserves) collapsed. Recovered within days.
• Generally considered the “safer” centralized option due to transparency

Other fiat-backed:

Crypto-Backed (Decentralized)

Instead of fiat reserves, these stablecoins are backed by cryptocurrency deposits locked in smart contracts.

DAI (MakerDAO)

• Backed by over-collateralized crypto deposits (ETH, WBTC, USDC, and others)
• For every $1 of DAI, there’s at least $1.50 in collateral locked in a “vault”
• If collateral value drops too close to the loan, it gets liquidated automatically
• Governed by MKR token holders through a DAO
• Truly decentralized — no company can freeze or seize DAI

How crypto-backed works:

1. You deposit $15,000 in ETH into a MakerDAO vault
2. You mint up to $10,000 in DAI (150% collateralization ratio)
3. If ETH drops and your collateral falls below 150%, your vault gets liquidated
4. When you repay DAI + stability fee, you get your ETH back

Collateral: $15,000 ETH
    │
    ▼
┌──────────────────┐
│  MakerDAO Vault  │ ──→ Mint $10,000 DAI
│  (Smart Contract)│
│  150% ratio min  │
└──────────────────┘
    │
    ▼
If ETH drops 35%: Vault liquidated → DAI holders protected

LUSD (Liquity)

• Backed only by ETH (no USDC in reserves)
• Fully immutable — no governance, no admin keys, no one can change the protocol
• Minimum 110% collateralization ratio
• One-time borrowing fee instead of ongoing interest

Algorithmic Stablecoins

These attempt to maintain their peg through algorithms and incentive mechanisms rather than reserves.

Warning: Most algorithmic stablecoins have failed catastrophically.

The Terra/UST collapse (May 2022):

• UST was an algorithmic stablecoin pegged to $1
• The mechanism: burn $1 of LUNA to mint 1 UST, and vice versa
• When UST slightly depegged, a “death spiral” began — people rushed to redeem UST for LUNA, crashing LUNA’s price, which reduced confidence in UST, which caused more redemptions…
• In 5 days, $40 billion in value was destroyed
• UST went to $0.02, LUNA went to near zero
• It was the largest single-event loss in crypto history

The lesson: algorithmic stability mechanisms work until they don’t, and when they fail, they fail completely.

FRAX: A partially algorithmic, partially collateralized model that has been more stable, though it has increasingly moved toward full collateralization.

How Stablecoins Maintain Their Peg

The Arbitrage Mechanism (Fiat-Backed)

If USDT trades at $0.99:

1. Traders buy USDT at $0.99
2. Redeem directly from Tether for $1.00
3. Profit: $0.01 per token
4. Buying pressure pushes USDT back to $1.00

If USDT trades at $1.01:

1. Traders send $1.00 to Tether
2. Receive 1 USDT
3. Sell on the market at $1.01
4. Profit: $0.01 per token
5. Selling pressure pushes USDT back to $1.00

This arbitrage loop keeps the price anchored — as long as people trust they can actually redeem for $1.

Smart Contract Mechanisms (Crypto-Backed)

DAI maintains its peg through several mechanisms:

• Over-collateralization: Every DAI is backed by more than $1 in collateral
• Liquidation: When collateral ratios drop too low, vaults are liquidated, reducing DAI supply
• Stability fee: Interest rate on DAI borrowing — raised to reduce supply (strengthen peg), lowered to increase supply (weaken if above peg)
• DAI Savings Rate (DSR): Interest earned by holding DAI — increased to attract demand (strengthen peg)

Risks of Stablecoins

Depegging

No stablecoin peg is guaranteed. History of depeg events:

Regulatory Risk

Governments are increasingly regulating stablecoins:

• The EU’s MiCA regulation requires stablecoin issuers to hold reserves in EU banks
• US legislation has been proposed requiring bank-like licensing
• Some stablecoins have frozen addresses at law enforcement request (USDT and USDC can blacklist addresses)

Counterparty Risk (Centralized)

When you hold USDT or USDC, you’re trusting:

• The issuer to actually hold the reserves they claim
• The banks holding reserves to remain solvent
• The issuer to honor redemptions
• The issuer not to freeze your address

Smart Contract Risk (Decentralized)

When you hold DAI or LUSD, you’re trusting:

• The smart contract code has no exploitable bugs
• The oracle feeds (price data) are accurate
• The collateral assets maintain their value
• The liquidation mechanism functions under stress

Stablecoins on Different Chains

The same stablecoin exists on multiple blockchains, with different properties:

When sending stablecoins, always verify the network. Sending USDT on the Ethereum network to a Tron address will lose your funds.

Key Takeaways

1. Stablecoins maintain a ~$1 value and are the most-used category of crypto by transaction volume
2. Fiat-backed (USDT, USDC) are backed by reserves — transparent to varying degrees
3. Crypto-backed (DAI, LUSD) use over-collateralization and smart contracts — more decentralized but more complex
4. Algorithmic stablecoins have mostly failed — the Terra/UST collapse destroyed $40 billion
5. All stablecoins carry risks: depegging, regulatory action, counterparty failure, or smart contract bugs
6. For transfers, Tron and Solana offer the cheapest USDT fees; for DeFi, Ethereum and its L2s dominate

FAQ

Q: Is USDT safe? A: USDT has maintained its peg since 2014 through multiple market crashes. However, Tether’s reserve transparency is lower than USDC’s, and the company has faced regulatory action. It’s the most liquid stablecoin but not the most transparent. For long-term holding, USDC may be a safer choice due to its regulated status and audited reserves.

Q: Can stablecoins go to zero? A: Fiat-backed stablecoins backed by actual reserves (USDT, USDC) are unlikely to go to zero as long as the reserves exist. Algorithmic stablecoins can and have gone to zero (UST). Crypto-backed stablecoins are protected by collateral but could fail in extreme market conditions.

Q: Do stablecoins earn interest? A: Not by default, but you can earn interest by depositing them in DeFi lending protocols (Aave, Compound) at 3–10% APY, or through the DAI Savings Rate (~5% APY). Exchanges also offer savings products for stablecoins.

Q: Why not just use regular dollars? A: Dollars on blockchain are more accessible (no bank required), faster (24/7 settlement), cheaper for international transfers, and programmable (can be used in smart contracts). Regular dollars are better for brick-and-mortar spending and are insured by deposit insurance programs.

Q: Are stablecoins taxable? A: Holding stablecoins generally isn’t taxable. But interest earned from DeFi lending or staking stablecoins is taxable income in most jurisdictions. Selling a stablecoin at a price different from your cost basis (rare but possible during depeg events) creates a capital gain or loss.