Saffron.finance is a decentralised finance protocol that separates the future yield of an asset into fixed and variable positions. Its fixed income vaults use an on-chain reverse zero-coupon swap structure, where one party receives a fixed payment upfront and another party purchases the right to the future yield generated by deposited assets.

The protocol initially uses Uniswap V3 liquidity positions as its underlying yield source. Each vault combines deposits from two sides. The fixed side supplies the assets used to create the Uniswap position and gives up the trading fees that the position may earn during the vault term. The variable side pays an upfront premium to the fixed side in exchange for those future fees.

Once both sides of a vault are fully funded, the deposited assets are deployed into the underlying Uniswap position. The fixed side can claim the premium at the beginning of the term, while the variable side receives the fees produced by the liquidity position. At maturity, the underlying assets become available to the fixed side again.

The premium paid to the fixed side can be expressed as an annualised fixed rate. The variable side’s return depends on how much yield the underlying position produces compared with the premium paid. When the position generates more fees than the cost of the premium and applicable protocol fees, the variable side earns a return. When it generates less, the variable side may lose some or all of the capital used to fund the premium.

Saffron vaults are designed to be permissionless, immutable and non-upgradeable. Fixed and variable deposits are represented by standard ERC-20 tokens, allowing the positions to be transferred, traded, used in other compatible DeFi applications or potentially used as collateral where external markets support them.

SFI, also known as Spice, is the native token of Saffron.finance. It is used for governance within the Saffron DAO and is separate from the fixed and variable position tokens created by the vaults.

SFI is used by holders to participate in governance. This can include voting on protocol parameters, treasury decisions and proposals concerning the development or management of Saffron.finance.

The wider Saffron protocol is used to structure positions around the future income of productive assets. Its vault model can be used to:

• Earn an upfront payment by selling the future yield of a productive asset;
• Incentivise on-chain liquidity for token issuers by structuring payments around future trading fees;
• Buy a hedge before an adverse price movement affects an existing holding;
• Create a bespoke options contract where deposited collateral continues earning swap fees;
• Loop liquidity to seek additional yield while accepting greater path dependency;
• Borrow against yield expected to be earned in the future;
• Purchase the future fees generated by a Uniswap liquidity position;
• Create a fixed-rate position without relying on continuing token emissions;
• Separate principal exposure from future fee income;
• Use tokenised fixed or variable positions in other compatible DeFi applications.

A token issuer can use a vault to support on-chain liquidity by offering participants exposure to future trading fees. A liquidity provider can accept an upfront payment instead of retaining uncertain future fee income. A variable-side participant can pay the premium to gain exposure to the fees earned by a larger underlying liquidity position.

The options use case allows deposited collateral to remain productive while supporting a customised contract. Instead of leaving collateral idle, the assets can continue generating swap fees through an underlying liquidity position during the contract term.

Looping liquidity involves reusing or borrowing against tokenised positions to increase exposure. This can increase potential returns, but it also creates greater path dependency because the outcome depends on the order and timing of market movements, vault maturities, reinvestment decisions and borrowing conditions.

Borrowing against future yield depends on an external lending market accepting the relevant tokenised position as collateral. This is a potential use of the vault assets rather than a lending function provided directly by Saffron.finance.

The fixed payment does not remove all risk. The underlying Uniswap position remains exposed to changes in the relative prices of its assets, concentrated-liquidity range risk and possible losses compared with simply holding the tokens. The variable side may lose capital if the underlying position earns insufficient fees. Smart-contract, network, token and integration risks also remain.

Vault duration also affects each side differently. Shorter variable-side positions can produce higher annualised returns when the underlying position performs well, but they are more exposed to individual periods of weak fee generation. Longer positions combine performance over more time, which can reduce the effect of a single unfavourable period. For the fixed side, longer terms can provide a larger upfront payment but may also increase exposure to changes in the value of the underlying liquidity position.

Saffron.finance was introduced in 2020 as a protocol for separating risk and yield in decentralised finance. Its earlier design allowed participants to choose different levels of exposure to the performance and risks of yield-generating strategies.

The fixed income vault model was developed by Saffron Finance contributors Rx3a97 and Psy Keeper. It applies a reverse zero-coupon swap structure, exchanging a fixed upfront payment for the future yield of an underlying financial position.

The first vault design focused on Uniswap V3 trading fees, although the model can support other yield-generating instruments. The protocol is governed through the Saffron DAO, where SFI holders can take part in decisions concerning its operation and development.