2026 stablecoin transparency rankings: USDC leads, USDT lowest

A 2026 stablecoin transparency index ranks major issuers on reserve disclosure, attestation quality, regulatory oversight, on-chain verifiability and governance. Circle’s USDC is highest on the index. Tether’s USDT is placed in the lowest tier among large fiat-pegged tokens.

The index weights reserve composition disclosure depth at 30 percent, attestation frequency and auditor quality at 25 percent, regulatory oversight and licensing at 25 percent, on-chain verifiability at 10 percent and operational and governance transparency at 10 percent.

USDC reserves were reported at about $76.7 billion with $76.5 billion in circulation in May 2026. Approximately 80 percent of reserves are held in the BlackRock Circle Reserve Fund, a SEC-registered government money market fund custodied at BNY Mellon; the rest is cash. Circle publishes monthly attestations prepared by Deloitte, weekly reserve updates and daily SEC filings for the fund. Circle National Trust received federal OCC approval on July 10, 2026. USDC also holds MiCA EMT authorization and had an S&P Global stability rating of 2 in December 2025.

Tether’s USDT remained the largest single stablecoin by supply at roughly $184 billion in mid-2026. Q1 2026 disclosures showed about $141 billion in U.S. Treasury and short-term exposures and roughly $50.5 billion in non-Treasury assets that included about $8 billion in gold and about $7 billion in Bitcoin, plus secured loans and equities. Tether reported excess reserves of $8.23 billion. Attestations are quarterly engagements by BDO Italia that verify reserves on a specific reporting date; the Q1 attestation covered March 31 and was published May 1, creating a 31-day publication lag. Tether announced in March 2026 that it engaged KPMG for a full financial statement audit and retained PwC to strengthen internal controls. As of mid-2026 no completed full financial audit had been released. Tether moved its headquarters to El Salvador and lists oversight under the CNAD, and it does not hold NYDFS, OCC, MAS or MiCA authorizations.

Mid-tier issuers in the index include Paxos-backed tokens and Standard Custody’s RLUSD. Paxos tokens such as PYUSD and USDG are reported as 100 percent backed by dollar deposits, short-term Treasuries and cash equivalents in segregated, bankruptcy-remote accounts. Monthly attestations for Paxos tokens are prepared by WithumSmith+Brown. Paxos holds a NYDFS trust charter, a MAS license, MiCA authorization for Europe and conditional OCC approval. Standard Custody’s RLUSD is reported as fully backed with reserves at BNY Mellon, publishes monthly attestations and holds NYDFS and conditional OCC credentials along with other regional licenses.

On-chain models differ in verification. Sky Protocol’s USDS allows public, real-time verification of collateral held in smart contracts, while an increasing allocation to tokenized real-world assets introduces off-chain elements for that portion of collateral. Ethena’s USDe uses a delta-neutral derivatives structure tied to exchange counterparties and does not publish PCAOB attestations or hold major regulatory licenses.

Regulatory and standards developments in 2026 include AICPA publication of SC1–SC15 controls criteria in January 2026 and the GENIUS Act requirements for monthly public reserve composition disclosure, reserves held in eligible assets, monthly PCAOB-registered attestations performed under the AICPA controls framework, and either an OCC permit or state-qualified issuer certification for U.S. market access. MiCA requires monthly reserve disclosure and sets liquidity and eligible-asset rules for EMTs; tokens with reserve allocations that include Bitcoin and gold do not meet Article 38 eligibility and were excluded from MiCA-licensed EU exchanges after July 1, 2026.

The index notes a technical distinction between attestations and full financial audits: attestations confirm reserve balances on a specific date under agreed-upon procedures, while audits examine financial records and internal controls over a reporting period. No major fiat-backed stablecoin issuer had published a completed full financial statement audit by mid-2026. Market participants use the five-dimension framework to evaluate tokens for compliance and counterparty acceptance, and several issuers have announced audit or control engagements in 2026 that could affect future rankings.