The dollar, minted on crypto rails

Stablecoins sit outside the CoinSpectrum cryptocurrency ranking by design — a stablecoin is a claim pegged to a reference asset, not a chain with its own consensus. But the stablecoin listing tracks every material one, and the argument for why they're separated from cryptocurrencies rests on the numbers here. This piece is the plumbing: what backs each coin, where the reserve claim has broken before, and how the supply moves against Bitcoin's cycle.

Eleven years of supply

From near-zero in 2015 to ~$270B across the established coins by 2026 (the full market, including newer entrants, is ~$300B). Two surges stand out: the 2020–21 DeFi boom and the 2024–26 ramp after the GENIUS Act gave US issuers a federal framework.

The coins that cover ≥98%

After the two giants, no stablecoin tops $10B. Nine named coins reach 97% of supply; adding the next tier of Paxos-issued and minor coins clears 98.8%. Three backing models split the field.

Reserves versus supply — three trust models

Fiat-backed coins aim for 1:1; Tether reports a small excess buffer; the CDP coins (DAI, USDS) over-collateralize each debt position — not the token's reserves — and today blend crypto vaults with USDC and tokenized Treasuries; USDe is synthetic — backed by crypto plus a short-futures hedge rather than dollars in a bank.

Tether: real dollars versus everything else

"Backed 1:1 by the dollar" is the perception. The Q1 2026 attestation (31 March) shows USDT is backed by a mix: genuine dollar instruments (US Treasuries + cash) cover about 79 cents of every token; the rest is gold, Bitcoin and secured loans. Tether holds a small surplus on top.

Three tiers answer "how much is real dollars," depending on how strict you are: cash + deposits only ≈ $4.5B (just 2.5% of supply — a ~41× ratio); all dollar instruments (adding T-bills, repo, money-market) ≈ $145B (~79% of supply, the 1.26× ratio); total reserves $191.8B (104% of supply, but a quarter of that is gold, BTC and loans, not dollars). Why it matters: gold and Bitcoin are price-volatile, and secured loans are the line Tether pledged to eliminate by end-2023 but instead grew to ~$15B. In a redemption rush the dollar instruments are what redeem at par instantly; ~21% of backing would have to be sold into the market first.

For context: the CFTC found USDT was fully fiat-backed only 27.6% of the time in 2016–2018, and reserves were ~40–50% commercial paper (incl. Chinese-bank paper) until late 2022. A first full KPMG audit reportedly began in Q1 2026.

Every reserve type — and the supply it backs — over time

The same categories tracked across quarterly attestations, 2021 → Q1 2026. Total height is Tether's reserves (≈ USDT supply), so this is the reserve mix and the supply growth in one view. The defining shift is the commercial-paper-to-Treasuries switch — CP was roughly half the reserve in early 2021 and gone by late 2022 — followed by the recent climb of the gold and Bitcoin bands.

USDC — supply and reserves over time

USDC's reserve is far simpler than Tether's — essentially cash + short-dated US Treasuries. But it wasn't always: a May 2021 attestation showed only 61% cash, with the rest in Yankee CDs (13%), commercial paper (9%), corporate bonds (5%) and a little muni/agency paper. Under regulatory scrutiny Circle pledged in Aug 2021 to hold reserves 100% in cash and short-duration Treasuries, reflected from the September 2021 attestation onward. Today it's ~80% in the BlackRock-managed Circle Reserve Fund (Treasuries + overnight repo) and ~20% bank cash.

The CDP line — DAI and USDS, drawn apart from fiat

The market's two CDP (collateralized-debt-position) coins — DAI and its successor USDS, both from Sky (ex-MakerDAO) — work differently from every fiat coin above. A user locks collateral in a vault and mints the stablecoin against it at a 145–175% ratio. That over-collateralization is on the borrower's debt position, not on the token's reserves — it's a liquidation buffer for a loan, not a claim that Sky holds $1.40 in a vault per circulating dollar. And the collateral itself is no longer mostly crypto: as of Q1 2026 it's ~40% tokenized US Treasuries, ~38% USDC (held in the Peg-Stability Module), and only ~22% crypto. So ~78% of "decentralized" DAI/USDS ultimately rests on USDC or T-bills — the reason DAI tracked USDC down during the March 2023 SVB depeg.

The line between stablecoins and CDP, in scale: the entire CDP segment is ~$13B — DAI ~$4.4B + USDS ~$8.7B. Set against the fiat giants (USDT ~$190B, USDC ~$74B), all CDP stablecoins combined are only about 4–5% of the ~$300B market. The decentralized model is the conceptually distinct one, but it's a small corner of the supply — and, via the PSM and RWA, increasingly plumbed into the same Treasuries and USDC that back the centralized coins.

When backing failed

"Pegged to $1" is a claim about reserves, not a guarantee. The regulatory record shows the claim has broken before — most consequentially at the largest issuer.

The policy response was the GENIUS Act (signed July 2025), the first US federal stablecoin framework: it mandates 1:1 reserves, regular audits, and licensing for US issuers. USDC, PYUSD and RLUSD are built to it; Tether, offshore in El Salvador, is neither GENIUS- nor MiCA-compliant and faces EU delistings — yet still dwarfs every compliant rival.

Bitcoin price versus stablecoin supply

Plotted together since 2013: Bitcoin's price (log scale, left axis) against total stablecoin supply (right axis). Stablecoin supply is the "dry powder" of the crypto economy — it tends to swell into and through Bitcoin's advances and plateau or drain in its winters.

The relationship is suggestive, not mechanical: supply climbed from ~$5B (2019) to ~$150B at the 2021 top, held through the 2022–23 bear instead of collapsing with price, then resumed growth to ~$300B even as BTC peaked and rolled over in 2025–26. Stablecoins have become a structural dollar rail that no longer fully ebbs with Bitcoin's cycle — they keep growing on payments and yield demand, not just speculation.

Supply growth, phase by phase — and the 2025 divergence

Measured across each Bitcoin phase, the pattern that mattered for years was simple: stablecoin supply expands violently into BTC up-trends — it grew +543% ($22B → $139B) through the 2020–21 bull and +87% ($141B → $264B) through the 2023–25 bull, amplifying each advance as fresh dollars entered. The 2021–22 bear then produced the first-ever sustained contraction in stablecoin history — supply fell −21% from a $165B peak to a $131B trough as capital fled and Terra/FTX imploded. The break in the pattern is now: through the current −52% BTC decline, supply has stayed essentially flat (~$264B → $270B) rather than contracting.

Monthly correlation between BTC returns and supply growth is weak (~0.15) and slightly positive — supply doesn't track BTC tick-for-tick. The signal is in the regime: supply growth averages +6.0%/mo in BTC up-months vs +5.0%/mo in down-months, and supply expansions have historically led rallies (the dry-powder reading). The 2025–26 flat-supply-amid-falling-price is the anomaly worth watching: either dry powder waiting to redeploy, or evidence that stablecoins are now a payments-and-yield rail first and a crypto-beta proxy second.