Stablecoins 101: USDC vs USDT vs DAI, and why issuer choice matters

The word "stablecoin" makes them sound interchangeable. They are not. A dollar in USDC, USDT, DAI, and FRAX are each backed by a different set of assets, governed by different entities, and exposed to different failure modes. For a yield strategy, picking which stablecoins to hold is one of the consequential early decisions — arguably more consequential than which protocol to lend to.

This piece walks through the three most-used dollar stablecoins, how each maintains its peg, and what that means for someone trying to earn yield on them safely.

What "peg" actually means

A stablecoin maintains a $1 peg through one of three mechanisms:

1. Fiat-backed. The issuer holds dollars (or cash-equivalent assets) one-for-one against tokens in circulation. Redeemability is the peg: anyone holding a token can theoretically redeem it for $1, so arbitrage keeps the market price near $1.
2. Crypto-collateralized. The token is over-collateralized by other crypto assets, usually ETH or staked-ETH derivatives. Smart contracts liquidate collateral if the ratio drops. The peg is held by mint/redeem mechanics inside the protocol.
3. Algorithmic. Supply expands or contracts based on market price using a paired token or rebase mechanism. Without external collateral, these have a poor historical track record. We do not allocate to these.

USDC and USDT are fiat-backed. DAI is mostly crypto-collateralized (with a meaningful fiat-backed share). All three have held a tight peg through multiple stress events, but for different reasons.

USDC (Circle)

Backing: Cash and short-dated U.S. Treasuries held with regulated U.S. financial institutions. Monthly attestation reports from major audit firms.

Governance: Centralized issuance and redemption through Circle. Tokens can be frozen on addresses that appear on sanctions lists, and Circle has used that authority in practice.

Strengths: The most transparent reserves in the major stablecoin set. The shortest distance between "I want a dollar" and "I have a dollar" — direct redemption with Circle is open to institutional partners and propagates to retail through exchange rails.

Weaknesses: Counterparty risk concentrated in U.S. banks and Treasury. The March 2023 depegging during the Silicon Valley Bank failure is the most famous example — USDC briefly traded as low as $0.88 before reserves were confirmed accessible. Recovery was clean but the event made clear that fiat-backed isn't risk-free.

USDT (Tether)

Backing: Mixed — predominantly U.S. Treasury bills, some cash, some secured loans, some commercial paper historically (now reduced), some Bitcoin holdings disclosed in attestations.

Governance: Centralized issuance and redemption through Tether. Has frozen tokens at the request of law enforcement.

Strengths: Deepest liquidity of any stablecoin globally. The default settlement currency for most non-U.S. crypto markets. Operationally robust through every major crypto stress event of the last six years.

Weaknesses: Lower disclosure standards than USDC historically, though this has improved meaningfully since 2022. The composition of reserves is attested rather than audited in the strict sense. Regulatory posture outside the U.S. is more comfortable than inside; for U.S.-leaning users, USDC is generally preferred.

DAI (MakerDAO)

Backing: A mix of crypto collateral (mostly ETH and Lido staked-ETH derivatives, plus other assets in vaults), USDC held in the Peg Stability Module, and real-world assets held in regulated vehicles managed by the Maker DAO ecosystem.

Governance: The MakerDAO governance process — token-holder voting determines collateral types, collateralization ratios, stability fees, and emergency parameters.

Strengths: Native to DeFi. Mint and redeem mechanics live on-chain. The peg has held through several severe stress events, including events that took down algorithmic stablecoins entirely.

Weaknesses: Governance risk is real and non-trivial. The collateral mix has shifted significantly over time, and a meaningful percentage of DAI's stability has historically depended on USDC in the PSM — which means DAI inherits USDC's risk in part. The transition to "Sky" / USDS is an ongoing governance project; users should track the changes.

What this means for a yield strategy

vildX deposits accept USDC and USDT. We're conservative about which other stablecoins enter the strategy as it rebalances. Three principles:

1. Concentration limits. No single stablecoin exceeds a target allocation, regardless of how attractive the underlying yield looks. A depeg of any one stablecoin should not be a fund-level event.
2. Issuer diversity. Holding only one issuer's tokens is taking on one issuer's counterparty risk in full. Holding two halves it. The principle is the same as not banking exclusively with one bank.
3. Avoid weak-peg constructs entirely. Anything that depends on a paired token, a rebase mechanism, or thin collateral is excluded.

How to think about it as a user

If you're depositing into a yield product:

• Check what stablecoins the strategy holds, not just what you deposit. A protocol that accepts USDC but rebalances heavily into a riskier stablecoin is taking risk you might not have signed up for.
• Know which issuer's failure would hurt you. A USDC depeg and a USDT depeg are different events with different probabilities and different recovery paths.
• Don't over-index on yield differences between stablecoins. A 50 bps APY premium on a riskier stablecoin is not free. Sometimes it's actually the market pricing in the risk.

The simple version: all dollar stablecoins are not the same dollar. The difference between them is the entire reason careful allocation matters, and the reason we're picky about what ends up in the vault.