Fiat-Backed Stablecoins: Reserve Structure, Audit Requirements & Issuer Risk
Deep dive into the most common stablecoin type β USDT, USDC, EURC β and the trust model behind each.
Key Takeaways
- Fiat-backed stablecoins hold real-world assets (cash, T-bills) equal to circulating supply.
- Reserve quality varies widely β from short-term US Treasuries to commercial paper.
- Audit frequency and transparency are the key risk differentiators between issuers.
How Fiat-Backed Stablecoins Work
Fiat-backed (or "off-chain collateralized") stablecoins are the simplest and most widely used type. An issuer holds one US dollar (or equivalent assets) for every token in circulation.
The Trust Model
You are trusting:
- The issuer to actually hold the reserves they claim.
- The custodian (a regulated bank or trust company) to safeguard those assets.
- The auditor to independently verify the reserve composition.
USDT (Tether)
Tether is the largest stablecoin by market cap (~$120B). Its reserves have historically included commercial paper, secured loans, and digital tokensβnot just cash and T-bills. Tether has improved its reserve quality since 2021 regulatory scrutiny but remains less transparent than competitors.
USDC (Circle)
USD Coin is issued by Circle, a US-regulated money transmitter. USDC holds only cash and short-term US Treasuries, with monthly attestations from a Big Four accounting firm. It is widely considered the most transparent major stablecoin.
Reserve Composition Matters
During the March 2023 Silicon Valley Bank (SVB) collapse, Circle disclosed that $3.3 billion of USDC's reserves were held at SVB. USDC briefly depegged to $0.87 before the Federal Reserve's emergency backstop restored confidence. This single event demonstrated that reserve quality and diversification are as important as reserve quantity.