USDT (issued by Tether) and USDC (issued by Circle) are the two largest US-dollar stablecoins. Each one is meant to be redeemable for one dollar. The main difference is what sits behind that promise and how it is reported. Circle holds USDC reserves in cash and a government money market fund. It publishes holdings weekly and gets monthly third-party assurance. Tether backs USDT with mostly US Treasury-linked assets, but its reserves also include gold, bitcoin and secured loans, and it publishes a quarterly attestation. USDT is the larger of the two. On 25 October 2026 DefiLlama showed about $182.4 billion USDT in circulation against about $71.7 billion USDC.
The newest change is in regulation. On 21 October 2026 the US Office of the Comptroller of the Currency (OCC) finalised its rule implementing the GENIUS Act. The rule takes effect on 18 January 2027.
The latest development: US rules take effect in January 2027
- 18 July 2025: the GENIUS Act (Public Law 119-27) was signed into law. It is the first US federal framework for payment stablecoins.
- 21 October 2026: the OCC issued Bulletin 2026-50, announcing its final rule. It covers reserve assets, redemption, risk management, audits and reports, custody, capital and the supervision of foreign issuers. The rule is published in the Federal Register of 23 October 2026. Anti-money-laundering, Bank Secrecy Act and sanctions provisions are left to a separate rulemaking with the Treasury.
- 18 January 2027: the OCC rule takes effect.
The Act requires 1:1 reserve backing and limits the reuse of reserves. It requires monthly public reserve reports, examined by a registered public accounting firm and certified by the issuer's CEO and CFO. Permitted issuers may not pay interest or yield to holders. These points come from a law-firm summary of the Act (Loeb & Loeb), not from the statute text.
Tether has responded with a second token. On 27 January 2026 it launched USAT, a dollar stablecoin for the US market. USAT is issued by Anchorage Digital Bank, N.A., a federally chartered bank supervised by the OCC. Coverage of the launch reports that Tether says USDT itself is "progressing towards GENIUS Act compliance".
USDT and USDC at a glance
| USDT | USDC | |
|---|---|---|
| Issuer | Tether | Circle |
| First issued | 2014 | 2018 |
| In circulation (DefiLlama, 25 Oct 2026) | ~$182.4B | ~$71.7B |
| Largest chains by supply | Tron (~$92.5B), Ethereum (~$72.6B) | Ethereum (~$44.3B), Solana (~$6.7B) |
| Reserve reporting | Quarterly attestation by BDO | Weekly holdings disclosure, monthly assurance by a Big Four firm |
| Reserve assets | Mostly Treasury-linked, plus gold, bitcoin and secured loans | Circle Reserve Fund (BlackRock-managed money market fund) and bank cash |
What backs USDC
According to Circle's transparency page (data dated 22 October 2026), most USDC reserves are held in the Circle Reserve Fund (USDXX). This is a SEC-registered 2a-7 government money market fund managed by BlackRock. It can hold cash, short-dated US Treasuries and overnight Treasury repurchase agreements. The rest is cash, mostly at large banks.
Circle discloses reserve holdings weekly, together with mint and burn flows. A Big Four accounting firm provides monthly third-party assurance under AICPA attestation standards. The page does not name that firm. Older guides name Grant Thornton, but Circle's own page says Grant Thornton served as auditor from 2015 to fiscal 2022 and Deloitte & Touche has been auditor since then. On 25 October 2026 the 2026 monthly reports were posted only through August.
USDT and USDC side by side
How do the two largest dollar stablecoins differ on issuer, supply, chains, reserves and reporting?
| Stablecoin | Issuer | First issued | In circulation (DefiLlama, 25 Oct 2026) (USD) | Largest chains by supply | Reserve assets | Reserve reporting | Source |
|---|---|---|---|---|---|---|---|
| USDT | Tether | 2014 | $182.4B | Tron (~$92.5B), Ethereum (~$72.6B) | Mostly Treasury-linked, plus gold, bitcoin and secured loans | Quarterly attestation by BDO | |
| USDC | Circle | 2018 | $71.7B | Ethereum (~$44.3B), Solana (~$6.7B) | Circle Reserve Fund (BlackRock-managed money market fund) and bank cash | Weekly holdings disclosure, monthly assurance by a Big Four firm |
This table shows only what the article reports from the issuers' own disclosures and attestations, which are not full audits. Circulation figures change daily, and the table does not show which tokens will qualify under the GENIUS Act rules from 18 January 2027.
What backs USDT
Tether's latest published attestation covers balances at 30 June 2026. It was prepared by BDO and released on 31 July 2026. Tether's own announcement gives these figures:
- Total assets: $187,751,426,411
- Total liabilities: $183,641,897,215, of which $183,622,105,630 relate to tokens issued
- Excess reserves: about $4.11 billion, down from a record $8.23 billion at the end of Q1 2026
- Net operating profit for the quarter: about $1.5 billion
- Secured lending: cut by about $2.38 billion (15%)
- Gold holdings: more than 146 tons, after adding 14 tons in the quarter
Tether's announcement does not give a dollar figure for Treasuries or bitcoin. An attestation reports balances at one point in time and is not a full audit. Some coverage questioned why the buffer halved in one quarter, and Tether's release does not explain it.
Tether was previously incorporated in the British Virgin Islands. In January 2025 it announced it had obtained a licence in El Salvador and would move its headquarters there.
Can either one lose its $1 peg?
Yes. In March 2023 Circle disclosed that $3.3 billion of USDC reserves was held at Silicon Valley Bank, which regulators had closed. USDC fell to about $0.87 before recovering. It recovered after US authorities said all SVB depositors would be protected. Reports of the exact low vary between outlets. The episode showed that a fully reserved token can still lose its peg on the market when holders doubt they can redeem it.
How to think about the choice
- If reserve transparency matters most: USDC publishes holdings weekly and in narrower asset classes. USDT publishes quarterly and includes gold, bitcoin and loans, whose value moves with the market.
- If you need to move funds on a specific network: check where each token actually circulates. Most USDT supply is on Tron and Ethereum. Most USDC is on Ethereum, followed by Solana and Base.
- If you are in the US: watch which tokens qualify as permitted payment stablecoins once the GENIUS Act rules take effect on 18 January 2027. USAT is Tether's product built for that framework.
- For any holding: the platform or wallet holding the tokens is a separate risk from the issuer's reserves.
This article explains how the two tokens work and is not investment advice.
Limitations: reserve data comes from the issuers' own disclosures and attestations, not full audits, and circulation figures change daily.
