USDC vs USDT for Corporate Treasury

For a corporate treasurer, a stablecoin is not an investment. It is a settlement instrument that needs to be worth a dollar when you spend it, redeemable for a dollar when you want out, and acceptable to your auditor, your bank and your regulator. Judged on those terms, the two largest dollar stablecoins have diverged sharply since 2025. This is a comparison on the criteria that matter for a company, not for a trader.

Size and trajectory

Tether's USDT remains far larger. On 3 September 2026 it had a market capitalisation of roughly USD 183 billion against USD 74 billion for Circle's USDC. The direction of travel is different, though. USDC grew about 72% year on year to mid-2026, its second consecutive year of outgrowing USDT, while USDT's supply drifted slightly lower over the first eight months of 2026. The gap is still more than two to one, but institutional flows are moving toward the smaller of the two.

Reserves and how you verify them

	USDC (Circle)	USDT (Tether)
Reserve composition	Roughly 80% short-dated US Treasuries and repo held in the Circle Reserve Fund, an SEC-registered government money market fund managed by BlackRock, with the remainder as cash at regulated US banks.	Roughly 80% US Treasuries, direct and via repo and money-market funds, plus cash equivalents, secured loans, gold and bitcoin.
Assurance	Monthly attestation by Deloitte. Daily holdings of the reserve fund are published by BlackRock.	Quarterly attestation by BDO Italia and a daily transparency page. Attestations are agreed-upon-procedures reports, not full audits. No completed full audit has been published as at September 2026, though Tether has said one is in progress.
Non-dollar assets in reserves	None.	Yes: gold, bitcoin and secured loans form a minority of reserves.

The practical difference is what your auditor can rely on. A monthly attestation of a portfolio you can see daily is close to bank-deposit standard of evidence. A quarterly point-in-time attestation of a portfolio that includes non-dollar assets is not, however well the peg has held.

Regulatory standing

United States: the GENIUS Act

The Guiding and Establishing National Innovation for US Stablecoins Act was signed on 18 July 2025 and is the first federal framework for payment stablecoins. Its core requirements: reserves of at least one to one in a narrow list of high-quality liquid assets, no re-use or lending of reserves beyond narrow exceptions, redemption on demand with proposed rules requiring it within two business days, and a prohibition on issuers paying holders yield simply for holding the coin. Regulators were directed to issue implementing rules by July 2026. The FDIC approved its proposed rule for the issuers it supervises on 7 April 2026 with a 60-day comment period, and the Act's requirements take effect no later than January 2027.

Circle has positioned USDC to operate inside that framework from the start. Tether announced a separate US-issued product in 2025 aimed at GENIUS compliance, but USDT itself is issued offshore and is not a permitted payment stablecoin under the Act. For a company that wants to hold or settle in a US-regulated instrument, that distinction will matter more each quarter as enforcement approaches.

European Union: MiCA

The Markets in Crypto-Assets Regulation has applied to stablecoins since 30 December 2024. Authorised crypto-asset service providers may only offer e-money tokens issued by an authorised issuer. USDC is authorised through Circle's French entity and is available on EU-regulated venues. Tether did not seek MiCA authorisation for USDT, and major EU-facing exchanges including Coinbase, Kraken and Binance's EEA platform delisted it for European customers; further platforms followed ahead of the 1 July 2026 transition deadline. Holding USDT in self-custody in the EU remains legal, but a European counterparty on a regulated venue increasingly cannot accept it.

Liquidity, chains and redemption

USDT has deeper spot liquidity on most centralised exchanges and dominates trading pairs outside the US and EU. USDC has deeper liquidity in regulated venues, in decentralised finance on Ethereum and its rollups, and in institutional settlement. Both are issued natively on multiple chains; Circle's cross-chain transfer protocol burns and mints natively rather than bridging, which reduces the wrapped-asset risk treasurers rightly dislike. Direct redemption with the issuer requires an onboarded institutional account with either company; most corporates redeem through a bank or a regulated on-ramp partner instead, and that partner's terms matter more than the issuer's.

Yield

Neither coin pays interest to holders, and under the GENIUS Act a US-permitted issuer cannot. Yield on stablecoin balances comes from what a platform does with the balance on your behalf: rewards programmes, money-market sweeps or treasury products. Treat any such yield as a separate product with its own risk, disclosure and accounting, not as a property of the coin.

Accounting and controls

Classification: most auditors treat dollar stablecoins as a financial asset or, where redeemable on demand at par through a regulated channel, as cash-equivalent-like. Agree the treatment before you hold a balance.
Wallet control: use a custodian or a platform with verified wallets, multi-party approval and address whitelisting. Self-custody by a finance team is a control failure waiting to happen.
Counterparty screening: every inbound stablecoin payment should pass the same screening as an inbound wire, and outbound payments to unverified addresses should be blocked by policy.
Conversion policy: define when stablecoin balances are converted to fiat and at what threshold, so operating cash is never stranded in an instrument your payables cannot use.

A treasurer's decision rule

Use USDC where regulatory standing, auditability and US or EU counterparties matter, which for a Cayman fund, SPV or holding company is most of the time. Use USDT where a specific counterparty or corridor requires it, in size limited to that need, and convert promptly. Hold neither as a long-term store of value: the point of a stablecoin in treasury is to move and settle, and the balance sheet belongs in deposits and regulated treasury products.

Where Mosaic fits

Mosaic's platform lets an entity hold an on-platform stablecoin balance or USDC alongside its US-dollar operating account, settle between them with verified wallets and approval controls, and convert to fiat before an expense is paid. Off-platform stablecoins move on and off the platform subject to the account configuration. Talk to our team about how your structure should be set up.

Sources

This article is general information as at its publication date and not legal, tax, regulatory or investment advice. Requirements and figures change; confirm current rules with a licensed Cayman Islands adviser and the relevant institution before acting.