Stablecoins are the quiet workhorses of crypto. While Bitcoin and Ether swing by double-digit percentages in a week, the two largest stablecoins — Tether's USDT and Circle's USDC — are designed to stay worth one US dollar, day after day. They are used to move money between exchanges, to park funds without leaving the crypto ecosystem, and increasingly to send payments across borders. This guide explains what backs them, how the peg actually works, and where the risks hide.
What a Stablecoin Is Backed By
USDT and USDC are both fiat-backed stablecoins: for each token in circulation, the issuer claims to hold roughly one dollar's worth of reserves. The details differ. USDC's reserves are held mostly in cash and short-term US Treasury securities, and Circle publishes regular attestations from an independent accounting firm describing what those reserves contain. USDT's reserves are broader: Tether holds a large share in US Treasuries as well, but its portfolio also includes other assets such as secured loans and, in smaller amounts, Bitcoin and gold. Both issuers publish reserve reports, but the depth and frequency of independent verification is not identical, and that gap is the single most important difference between the two from a risk standpoint.
The redemption mechanism is what keeps the price at one dollar. If USDC trades below a dollar on an exchange, traders can buy it cheap, redeem it with Circle for a full dollar, and pocket the difference. That buying pressure pushes the price back up. If it trades above a dollar, the reverse happens: anyone can mint new USDC by depositing a dollar, sell the token at a premium, and the extra supply pushes the price down. The peg is not magic — it is arbitrage, repeated thousands of times a day by traders who profit from keeping it tight.
The Risks People Underestimate
The first risk is the issuer itself. A stablecoin is only as solid as the company behind it and the reserves it holds. If an issuer's reserves turned out to be worth less than the tokens in circulation, or if the issuer became unable to process redemptions, the peg could break — and it has broken before, briefly, for both major coins during moments of market stress. The history here is reassuring in one sense (both coins recovered) and cautionary in another (the peg is a promise, not a law of physics).
The second risk is regulatory. Stablecoins sit at the intersection of banking, securities, and payments law, and rules differ sharply by country. Issuers can be ordered to freeze specific addresses — both Tether and Circle have done so under law-enforcement requests — which means a stablecoin in your wallet is not quite the same as cash in your pocket. It is closer to a balance at a regulated financial institution, with all the compliance machinery that implies.
The third risk is operational: smart-contract bugs in the token's code, a compromised bridge when moving between blockchains, or an exchange that goes down while you need to exit. None of these are risks of the peg itself, but they are risks of using stablecoins in practice, and they are the ones most newcomers overlook.
Why it matters
Stablecoins are where crypto meets everyday money. Understanding the difference between USDT and USDC — reserve composition, transparency, and the redemption mechanism — is the difference between treating them as interchangeable dollars and treating them as what they are: liabilities of two different companies, each with its own balance sheet. For most users, either coin works fine for trading and transfers. But if you plan to hold a meaningful amount for any length of time, the boring questions matter most: who holds the reserves, what exactly is in them, and how quickly can you get your dollar back? Answer those before you decide which stablecoin to trust with your money.
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