The dollar-pegged stablecoin market reached approximately $316 billion in total capitalization by June 2026, with Tether USDT at $187 billion and Circle USDC at $75 billion controlling 83% of supply, according to DefiLlama on-chain data. The GENIUS Act, signed into law on July 18, 2025, transformed stablecoins from a regulatory gray zone into licensed financial instruments requiring 100% liquid reserves, monthly public attestations, and federal or state regulatory oversight. Transaction volumes in 2025 approached $46 trillion, rivaling Visa's annual throughput and the U.S. ACH network, according to a16z.
Fiat-Collateralized Stablecoins Hold Cash and Treasury Reserves
Fiat-collateralized stablecoins hold reserves of cash and cash equivalents in bank accounts and money market funds. Each token in circulation corresponds to one dollar in reserves. Tether USDT leads the market at approximately $187 billion, commanding roughly 59% of total stablecoin supply. Circle's USDC follows at around $75 billion with a 24% share, per CoinLaw statistics updated June 2026.
Circle publishes USDC reserve holdings weekly with monthly Big Four attestation from Deloitte & Touche LLP since fiscal 2022. Tether refreshes USD circulation data daily and publishes quarterly attestation reports through BDO Italia. Tether held a $113 billion U.S. Treasury position as of Q1 2026, according to its quarterly attestation.
No other stablecoin holds even a 3% market share. Sky Dollar (USDS) sits near $8 billion, Ethena's USDe around $4.5 billion, and DAI at approximately $4.4 billion. PayPal's PYUSD remains below $3 billion. USDT dominates emerging markets and offshore trading, with over 60% of supply sitting on Tron. USDC is the default inside regulated U.S. and European fintech stacks, used primarily for institutional B2B settlement and treasury management.
Crypto-Collateralized and Algorithmic Models Use On-Chain Assets
Crypto-collateralized stablecoins like DAI use on-chain assets as backing. DAI requires overcollateralization at 155% in ETH and real-world assets, including bonds. When collateral values drop below liquidation thresholds, automated smart contracts sell the underlying assets to maintain the peg.
Algorithmic stablecoins use code rather than collateral to defend the peg. The category collapsed in May 2022 when TerraUSD lost its $18 billion market cap in 72 hours. As of 2026, surviving algorithmic and semi-algorithmic designs, including FRAX and USDD, have moved to hybrid models combining partial reserves with algorithmic adjustments. The entire category sits below $5 billion combined.
A separate class has emerged since 2024: synthetic dollar instruments. Ethena's USDe ($3.8 billion) shorts ETH perpetuals against staked ETH collateral for a market-neutral position. BlackRock's BUIDL ($2.8 billion) and Circle's USYC ($2.9 billion) are tokenized money market funds. The SEC's 2024 guidance and the GENIUS Act distinguish payment stablecoins from yield-bearing instruments, with the latter treated as securities or money market funds.
GENIUS Act Establishes Federal Reserve and Attestation Requirements
The GENIUS Act created the first comprehensive federal framework for payment stablecoins. Gibson Dunn described it as "the most significant United States law affecting the digital assets industry to date" in their November 2025 analysis. The law requires one-to-one reserve backing, monthly public disclosures, and examination by an independent accounting firm.
The GENIUS Act requires payment stablecoin issuers to register with federal or qualifying state regulators, maintain segregated reserves, submit to monthly attestations, and comply with Bank Secrecy Act anti-money laundering obligations. Payment stablecoins cannot pay interest or yield to holders. This separates them from tokenized money market funds and yield-bearing instruments.
The GENIUS Act takes effect on the earlier of 18 months after enactment (January 18, 2027) or 120 days after primary federal regulators issue final implementing rules. The OCC published its proposed rule in early 2026, with a comment period that closed in May. The FDIC and Treasury followed with separate proposals through April 2026.
OCC Granted National Trust Charters in December 2025
The OCC conditionally granted national trust bank charters to Circle, Paxos, and three other nonbank firms in December 2025, according to Brookings. This creates a path for stablecoin issuers to operate as federally regulated entities rather than relying on state money-transmitter licenses.
The EU MiCA framework imposes parallel requirements through its Title III provisions, mandating monthly composition disclosures and minimum deposit floors. Both frameworks directly affect which stablecoins can be offered to U.S. and European users.
Citi Projects Stablecoin Market Could Reach $1.9 Trillion by 2030
Citi projects the stablecoin market could reach $1.9 trillion by 2030 in its base case and $4 trillion in its bull case. Standard Chartered sees $2 trillion as early as end-2028. More than 140 companies, including Visa, Mastercard, Coinbase, and BlackRock, have joined the Open USD stablecoin project.
Circle is building Arc, a Layer 1 blockchain where USDC is the native gas token. Tether's counterpart is Stable, which launched mainnet in December 2025.
FAQ
What is the total stablecoin market capitalization as of June 2026?
The total stablecoin market reached approximately $316 billion by June 2026, with Tether USDT at $187 billion and Circle USDC at $75 billion controlling roughly 83% of the supply, according to DefiLlama on-chain data.
What does the GENIUS Act require of stablecoin issuers?
The GENIUS Act, signed into law on July 18, 2025, requires payment stablecoins to maintain 100% liquid reserves, undergo monthly public attestations by independent accountants, operate under federal or qualifying state regulators, and comply with Bank Secrecy Act anti-money laundering obligations. Payment stablecoins cannot pay interest or yield to holders.
What happened to TerraUSD in May 2022?
TerraUSD lost its $18 billion market cap in 72 hours in May 2022. Surviving algorithmic and semi-algorithmic designs, including FRAX and USDD, have moved to hybrid models combining partial reserves with algorithmic adjustments, with the entire category below $5 billion combined as of 2026.
