A stablecoin is a cryptocurrency whose price is pegged to the value of another asset, most often the US dollar. Instead of fluctuating like Bitcoin or Ether, a stablecoin is designed to stay at a fixed value — ideally one dollar for every dollar-pegged stablecoin — so that users can hold and transact in it without worrying about volatility. Stablecoins are the thing that makes crypto usable as a payment rail and a trading unit rather than purely as a speculative asset. Without stablecoins, crypto traders would have no on-chain cash equivalent to price things against, and most of DeFi would be impossible.
The total supply of dollar-pegged stablecoins is currently around $300+ billion as of 2026, up from near zero a decade ago, and they have quietly become one of the most-used products in crypto. Daily stablecoin transfer volume across chains is in the hundreds of billions of dollars, rivaling or exceeding the combined daily volume of major traditional payment networks for cross-border transfers. For a product category that barely existed eight years ago, the scale is impressive.
The Main Players
USDT (Tether) is the oldest and largest. Launched in 2014 originally on the Omni layer of Bitcoin, Tether is now issued on dozens of chains and has a supply of roughly $160-180 billion. Tether has been controversial throughout its history — concerns about its reserve composition, its relationship with Bitfinex, and its regulatory status have driven repeated “is Tether about to collapse” cycles that have never actually materialised. Tether now publishes quarterly attestations showing reserves, which are overwhelmingly dominated by US Treasuries, and it has become the de facto liquidity layer for international crypto trading even if it is never fully trusted by the most careful users.
USDC (USD Coin) is issued by Circle, a US-regulated company, with reserves held at US banks and regularly audited. USDC supply is in the $50-70 billion range and has been more popular with institutional and US-based users because of Circle’s tighter regulatory posture. USDC had a brief depegging event in March 2023 during the Silicon Valley Bank collapse, when some of Circle’s reserves were stuck at the failing bank — the stablecoin briefly dropped to around $0.88 before the Federal Reserve announced it would backstop SVB depositors and USDC recovered. The episode was a real stress test and USDC survived it intact, but it was also a reminder that even a “safe” stablecoin depends on the traditional banking system it is backed by.
DAI (now rebranded as USDS in the Sky ecosystem) is the largest non-custodial stablecoin, issued by MakerDAO/Sky through a smart-contract-based system that accepts over-collateralised crypto deposits and mints DAI against them. DAI has a supply of roughly $5-8 billion and has held its peg reasonably well across multiple cycles, though its reliance on centralised reserves (USDC is a significant part of DAI’s backing) has made it less “pure crypto” than the original design intended.
PYUSD (PayPal USD) and FDUSD (First Digital USD) are more recent entrants with smaller but growing supply. Ethena’s USDe is a more experimental stablecoin that uses delta-neutral hedging on crypto collateral to maintain its peg — a model that worked through 2024-2025 but remains unproven across a full cycle.
How the Pegs Actually Work
The short version: reserve-backed stablecoins work because the issuer holds real dollars (or equivalent assets) and will redeem tokens for dollars at par, and this redemption mechanism lets arbitrageurs keep the market price near $1. If the secondary market price drops to $0.995, an arbitrageur buys USDC cheaply, redeems it with Circle at par for $1, and pockets the 0.5 cents. The arbitrage drives the price back up. The mechanism requires the reserves to be real, the redemption process to actually function, and enough market participants to be doing the arbitrage.
Over-collateralised stablecoins like DAI work similarly but with crypto collateral instead of fiat. If DAI drops below $1, anyone with a vault can profitably close their position by buying cheap DAI and repaying the loan, which removes DAI from circulation and drives the price back up.
Algorithmic stablecoins — the ones that try to maintain a peg without any collateral at all — have a much worse track record. Terra’s UST is the most notorious case. UST’s peg was maintained by an arbitrage loop with LUNA that worked in calm conditions and collapsed catastrophically when stressed in May 2022, destroying roughly $60 billion in value over a single week and taking several other crypto firms down with it. Since Terra, the algorithmic stablecoin category has essentially been discredited, and most serious projects have moved back to some form of collateral backing.
Why Stablecoins Became the Killer App
The original Bitcoin vision was to be digital cash — a currency people could use for payments without intermediaries. Bitcoin’s volatility made that vision hard to realise in practice: a currency whose price can swing 10 percent in a day is not well-suited to paying for coffee or running a payroll. Stablecoins quietly solved that problem by giving crypto users a stable unit of account while preserving all the other benefits of on-chain transactions — programmability, borderless transfers, low fees (on L2s), and integration with DeFi.
The result is that stablecoin transfers now dwarf bitcoin transfers as a share of useful on-chain activity. Remittance flows to developing markets routinely route through stablecoins because they are faster and cheaper than traditional rails. DeFi protocols denominate their yields in stablecoins. Merchants who accept crypto overwhelmingly accept stablecoins. For most of the “crypto actually doing something useful” stories — people in Argentina escaping peso inflation, people in Nigeria bypassing dysfunctional banking, people in the Philippines receiving remittances from workers abroad — the thing that is actually moving is not Bitcoin but a dollar-pegged stablecoin. The irony is that the biggest real-world use of crypto turned out to be digital dollars, not a replacement for dollars, and the industry has been slowly making peace with that.