A stablecoin is a cryptocurrency designed to hold a stable value, usually pegged 1:1 to a fiat currency like the US dollar. Unlike Bitcoin or Ethereum, a stablecoin isn't meant to appreciate — its entire purpose is to behave like digital cash, making it useful for trading, payments, and moving value without exposure to crypto's usual volatility. Tether (USDT) and USD Coin (USDC) are the two largest by market capitalization.
The three main designs
- Fiat-collateralized — the issuer holds reserves (cash, short-term treasuries) equal to the coins in circulation, and redeems coins for dollars on request. USDT and USDC both work this way.
- Crypto-collateralized — the coin is backed by other cryptocurrencies locked in a smart contract, typically over-collateralized (e.g. $150 of ETH backing $100 of stablecoin) to absorb price swings in the collateral.
- Algorithmic — the peg is maintained through supply-and-demand mechanisms and incentives rather than a reserve asset. This design has a poor track record — TerraUSD's 2022 collapse is the best-known example of an algorithmic stablecoin losing its peg entirely.
Why it matters for Shariah screening
The stablecoin itself — holding a digital dollar-equivalent — isn't inherently problematic; it's closer to a digital IOU or currency than a speculative asset. The Shariah questions cluster around two things: what backs it, and what you do with it. A fiat-collateralized stablecoin backed by reserves that themselves generate interest (e.g. treasury bills) raises a riba question at the reserve level, separate from the coin itself. And a stablecoin sitting idle isn't a concern — but depositing it into an interest-bearing lending pool or "earn" product is exactly the riba mechanism covered in Is Crypto Lending Halal?. Algorithmic stablecoins carry an additional gharar concern given how much their peg stability depends on unproven, sometimes circular incentive design rather than a hard, redeemable reserve.