sUSD is Synthetix's legacy synthetic US-dollar stablecoin, now being wound down and converted to vested SNX under governance proposal SIP-423.
| Symbol | sUSD |
| Peg | USD |
| Backing | Crypto backed |
| Status | Active |
| Launched | 2018 |
| Networks | L1 EVM Ethereum L2 Optimism |
| Specifications | Backing Legacy SNX-collateralized synthetic dollar backed by the Synthetix debt pool. Redemption Under SIP-423, frozen legacy sUSD is redeemed at $1 of value in SNX on Ethereum, with a one-year lock and one-year vesting schedule. KYC required No |
| Use cases | Trading, DeFi collateral |
| Mint and redeem | Historically minted against SNX staking via the shared debt pool; minting deprecated and legacy supply being converted to vested SNX under SIP-423. |
| Depeg history | Date 2025-03-31 · Low price 0.916 · Cause Transition-period peg instability and excess sUSD supply pressureDate 2025-04-28 · Low price 0.7 · Cause Reported impact of the SIP-420 protocol shift, lower collateralization, and liquidity outflows unverified |
| Chain | Supply |
|---|---|
| Ethereum | $47M |
| OP Mainnet | $23M |
## Overview sUSD is the legacy synthetic US-dollar stablecoin of the Synthetix protocol. It is being retired rather than actively expanded. ## How It Works Historically, sUSD was minted against SNX staking through the protocol's shared debt-pool accounting. Under SIP-423, legacy sUSD is frozen and holders are redeemed at one dollar of value in SNX, subject to a lock and vesting schedule. ## Reserve Backing sUSD was backed by SNX collateral and protocol debt accounting rather than fiat reserves. During 2025 it experienced significant peg instability before the retirement decision. ## Supported Networks sUSD exists on Ethereum and Optimism.