# sUSD0 > **Last updated:** 2026-02-16 *** ## Executive Summary **sUSD0** is the savings token for USD0, implemented as a **permissionless ERC-4626 vault**. Users deposit USD0 and receive sUSD0 shares representing a proportional claim on the vault's total assets. sUSD0 is **non-rebasing**: balances remain constant while value accrues through a rising exchange rate. Redeeming sUSD0 returns more USD0 than originally deposited, with the difference representing the accumulated yield. Yield originates from the protocol's revenue and is routed to sUSD0 holders via the vault's exchange-rate mechanism. Distribution parameters, including the rate of yield allocation, are governed by **Usual DAO** and may vary with market conditions and governance decisions. The yield is denominated in **USD0,** distinguishing sUSD0 from bUSD0 where yield is denominated in USUAL tokens. sUSD0 requires no lock-up: deposits and withdrawals are available at any time, subject to on-chain settlement and any applicable redemption fee (currently 3 bps). The ERC-4626 standard ensures broad DeFi composability with lending markets, yield routers, structured vaults, and Pendle-style PT/YT products. *** ## Key Facts | Parameter | Detail | | ---------------------- | ---------------------------------------------------------------------------------------------------------- | | **Token name** | sUSD0 (Savings USD0) | | **Token standard** | ERC-4626 (tokenized vault) | | **Decimals** | 18 | | **Issuer** | Usual DAO (governance-owned) | | **Underlying** | USD0 — RWA-backed USD stablecoin (T-Bills, USYC) | | **Value accrual** | Non-rebasing; exchange rate increases over time | | **Redemption math** | USD0 out = sUSD0 shares x exchangeRate (where exchangeRate >= 1) | | **Yield source** | Protocol revenue from T-Bill collateral and DAO allocation | | **Yield denomination** | USD0 (real yield) | | **Lock-up** | None — deposit and withdraw freely | | **Access** | Permissionless; no KYC/KYB required | | **Wrap fee** | Free | | **Redeem fee** | Up to 3 bps | | **Chain** | Ethereum | | **Governance** | 100% DAO-owned (UIP-15, Dec 2025) | | **Audits** | Hexens (sUSD0 audit, Nov 2025); Spearbit (Yield Module, Feb 2025); part of 20+ protocol-wide audit program | *** ## How sUSD0 Works ### Deposit (Wrap) ``` Deposit USD0 → Receive sUSD0 shares at current exchangeRate ``` sUSD0 shares represent a proportional claim on the vault's total USD0 holdings. The number of shares received is determined by the current exchange rate at time of deposit. ### Yield Accrual The vault's exchange rate increases over time as the protocol routes yield from DAO revenue (sourced from T-Bill collateral returns) into the vault. There are no claims to process and no manual actions required; value accrues passively. ### Withdrawal (Unwrap) ``` Burn sUSD0 → Receive USD0 at current exchangeRate (minus any redemption fee) ``` Because the exchange rate only increases, the USD0 received upon redemption exceeds the amount originally deposited (assuming positive yield over the holding period and net of fees). *** ## Yield Source & Collateral Stack ### Revenue Chain sUSD0 yield traces back to the real-world returns generated by the collateral backing USD0: ``` T-Bill Collateral (USYC, M, USTBL) + Protocol fees → Generates sovereign fixed-income yield + income → Captured as protocol revenue → Portion allocated to sUSD0 vault by DAO → Exchange rate increases → sUSD0 holder's USD0 claim grows ``` ### Collateral Composition USD0 is fully backed by short-duration U.S. Treasury Bills and equivalent sovereign instruments held through regulated tokenizers: | Collateral | Tokenizer | Regulatory Status | Custody | | ---------- | ------------ | ------------------------------ | ---------------- | | **USYC** | Hashnote | CIMA licensed, CFTC registered | BNY Mellon | | **$M** | M^0 Protocol | TTG governance | SPV-held T-Bills | | **USTBL** | Spiko | AMF authorized (France), UCITS | CACEIS Bank | ### Yield Characteristics | Property | Detail | | ----------------------- | -------------------------------------------------------------------------------------- | | **Denomination** | USD0 (real yield) | | **Source** | T-Bill collateral returns allocated by DAO | | **Variability** | Variable; depends on collateral yields and governance-set allocation | | **Guarantee** | Not guaranteed — subject to collateral performance and DAO decisions | | **Distribution method** | Automatic via exchange-rate increase; no claims required | | **Boost at launch** | Governance may temporarily boost the rate; convergence to sustainable levels over time | *** ## sUSD0 vs. bUSD0 | Dimension | sUSD0 | bUSD0 | | -------------------------- | ------------------------------------------- | ---------------------------------------------------- | | **Mechanism** | ERC-4626 vault; exchange-rate accrual | Liquid bond; daily USUAL token coupons | | **Lock-up** | None | Bond with maturity (June 2028) | | **Yield denomination** | USD0 (real yield) | USUAL tokens (alpha yield) | | **Yield type** | Predictable, T-Bill-based | Variable; dependent on USUAL token price | | **Early exit** | Instant redemption at current exchange rate | Secondary market sale or recombination with rt-bUSD0 | | **Token price volatility** | Minimal — exchange rate only increases | May trade at discount to par before maturity | | **DeFi composability** | High (ERC-4626 standard) | High (tradeable ERC-20; usable as collateral) | sUSD0 is designed for participants seeking **stable, predictable yield denominated in USD0**, with no lock-up and no direct exposure to token price volatility. bUSD0 is designed for participants willing to commit capital for potentially higher returns driven by USUAL emissions and bond discount dynamics. *** ## sUSD0 vs. USD0 Rebasing Track The protocol also supports a **rebasing mode** where yield is distributed directly to USD0 balances at the cash layer, without wrapping into a vault token. The rebasing track is a separate feature: | Dimension | sUSD0 (Accruing) | USD0 Rebasing | | -------------------- | ----------------------------------- | ------------------------------------------- | | **Access** | Permissionless | KYC/KYB required ($100K+ minimum) | | **Yield method** | Exchange-rate accrual (no claims) | Claim-based via Brevis ZK proofs (Incentra) | | **Balance behavior** | Fixed balance, rising exchange rate | Balance increases directly | | **Use case** | DeFi-native composability | Institutional wallets, payment interfaces | *** ## Fees | Fee | Amount | Notes | | ------------------- | ----------- | ---------------------------------------- | | **Wrap (deposit)** | 0 bps | No fee to deposit USD0 into sUSD0 vault | | **Unwrap (redeem)** | Up to 3 bps | Governance-configurable; currently 0 bps | | **Network gas** | Variable | Standard Ethereum gas costs apply | *** ## Smart Contract Addresses ### sUSD0 Token | Chain | Address | | ------------ | -------------------------------------------- | | **Ethereum** | `0xd861bE82dEe3223CFBEd160791f6550b0704D406` | ### Related Contracts (Ethereum) | Contract | Address | | --------------------- | -------------------------------------------- | | **USD0 (underlying)** | `0x73A15FeD60Bf67631dC6cd7Bc5B6e8da8190aCF5` | | **USUAL** | `0xC4441c2BE5d8fA8126822B9929CA0b81Ea0DE38E` | | **YieldModule** | `0x647F8987C288bf6D2fDb332918E1E14424839EDA` | | **DaoCollateral** | `0xde6e1F680C4816446C8D515989E2358636A38b04` | ### Oracles (Ethereum) | Oracle | Address | | ------------------------- | -------------------------------------------- | | **ClassicalOracle** | `0xb97e163cE6A8296F36112b042891CFe1E23C35BF` | | **Chainlink USD0 Oracle** | `0x7e891DEbD8FA0A4Cf6BE58Ddff5a8ca174FebDCB` | *** ## Key Risks | Risk Category | Description | Mitigation | | ------------------------------ | ------------------------------------------------------------------------------------------------ | ------------------------------------------------------------------------------------------------------------------------ | | **Yield variability** | Returns depend on T-Bill collateral yields and DAO allocation decisions; yield is not guaranteed | Sovereign collateral generates stable base yield; governance-set parameters ensure sustainability | | **Underlying collateral risk** | Adverse event at a tokenizer or custodian could impair USD0 collateral value | Diversified tokenizer base (Hashnote, M^0, Spiko); Insurance Fund (0.33-5.33% of USD0 supply); zero credit/FX tolerance | | **Interest rate risk** | Rising rates reduce mark-to-market value of T-Bill holdings, potentially reducing yield | Max portfolio duration <= 0.33 years; stress-tested for +100 bps shock | | **Smart contract risk** | Vulnerability in sUSD0 vault, YieldModule, or underlying USD0 contracts | sUSD0 audited by Hexens (Nov 2025); Yield Module audited by Spearbit (Feb 2025); part of 20+ protocol-wide audit program | | **Peg risk** | USD0 may temporarily deviate from $1 on secondary markets | Arbitrage incentives; Insurance Fund; Counter Bank Run (CBR) mechanism; 5-day max redemption horizon on collateral | | **Oracle risk** | Incorrect price feed could affect USD0 valuation and by extension sUSD0 yield | Dual oracle system (ClassicalOracle + Chainlink); continuous monitoring with alert thresholds | | **Governance risk** | DAO decisions affecting yield allocation, redemption fees, or vault parameters | On-chain voting via UIPs; transparent proposal process; fee cap at 3 bps | | **Counterparty risk** | Failure of tokenizer, fund manager, custodian, or banking partner | Multi-provider diversification; regulated entities (BNY Mellon, CACEIS); rigorous due diligence framework | | **Regulatory risk** | Evolving regulatory landscape for stablecoins and yield-bearing instruments | Multi-jurisdictional tokenizer diversification (CIMA, AMF, CFTC); no leverage; full backing | *** ## Security & Audits sUSD0 is covered by the protocol-wide security program comprising **20+ independent audits** since May 2024. | Firm | Scope | Date | | ------------ | ------------------------------------------------------- | -------------------- | | **Hexens** | sUSD0 and sEUR0 audit | Nov 2025 | | **Spearbit** | Yield Module audit | Feb 2025 | | **Halborn** | RDM (Revenue Distribution Module) audit | Nov 2025 | | **Sherlock** | Multiple audit campaigns covering protocol-wide modules | Nov 2024 -- Nov 2025 | **Bug Bounty:** Active program via Sherlock Bug Bounties (audits.sherlock.xyz/bug-bounties). Triage and severity handled by Sherlock's security team. **Security contact:** *** ## Quick Links * sUSD0 — Product Overview: * Security & Audits: * Contract Deployments: * Etherscan — sUSD0: *** ## Disclaimer This factsheet is provided for **informational purposes only** and does not constitute investment advice, an offer to sell, or a solicitation of an offer to buy any security or financial instrument. sUSD0 is a decentralized protocol token governed by Usual DAO; participation involves risks including but not limited to smart contract risk, collateral risk, yield variability, and regulatory risk. Yields are variable and not guaranteed; past performance is not indicative of future results. The sUSD0 vault depends on protocol-level revenues, collateral performance, oracle and contract operations, and governance parameters. All smart contract addresses should be independently verified on the respective block explorers before interacting. 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