Return Model

The tranching return model maps utilization to the Junior share of residual Senior-side yield. The active model is stored in a separate ExponentTranchingMarketReturnModel account so larger piecewise curves do not live directly inside the main market account.

ExponentTranchingMarketReturnModel

pub struct ExponentTranchingMarketReturnModel {
    pub market: Pubkey,
    pub return_model: TrancheReturnModel,
    pub reserved: [u8; 128],
}

Field	Description
`market`	Main `ExponentTranchingMarket` this model belongs to
`return_model`	Active return allocation model
`reserved`	Reserved bytes for future compatibility

TrancheReturnModel

pub enum TrancheReturnModel {
    UtilizationGuidedCurve(UtilizationGuidedCurveParams),
    PiecewiseLinearCurve(PiecewiseLinearCurveParams),
}

UtilizationGuidedCurveParams

pub struct UtilizationGuidedCurveParams {
    pub junior_share_at_target_utilization: Number,
    pub last_target_shift_ts: i64,
    pub max_target_shift_speed: Number,
    pub zero_utilization_junior_share_discount: Number,
    pub full_utilization_junior_share_premium: Number,
}

Field	Description
`junior_share_at_target_utilization`	Junior return share at the fixed 90% target utilization
`last_target_shift_ts`	Timestamp used for target-shift accounting
`max_target_shift_speed`	Maximum target-share movement per second
`zero_utilization_junior_share_discount`	Discount applied below target at zero utilization
`full_utilization_junior_share_premium`	Premium applied above target at full utilization

PiecewiseLinearCurveParams

pub struct PiecewiseLinearCurveParams {
    pub points: Vec<u64>,
}

The piecewise model stores 1000 possible utilization-indexed points. Non-zero points define the curve. The program interpolates between the nearest initialized lower and upper points.

PiecewiseLinearCurvePoint

pub struct PiecewiseLinearCurvePoint {
    pub utilization: Number,
    pub y: Number,
}

Field	Description
`utilization`	Utilization value between `0` and `1`
`y`	Junior return share at that utilization

Update enum

Market initialization and modification use TrancheReturnModelUpdate:

pub enum TrancheReturnModelUpdate {
    UtilizationGuidedCurve(UtilizationGuidedCurveParams),
    PiecewiseLinearCurve(Vec<PiecewiseLinearCurvePoint>),
}

For PiecewiseLinearCurve, the update can pass only the points that should be set. The program stores them into the 1000-point backing array.

Tranching Basics

DeFi Integrations

Tranching SDK

Other Resources

ExponentTranchingMarketReturnModel

TrancheReturnModel

UtilizationGuidedCurveParams

PiecewiseLinearCurveParams

PiecewiseLinearCurvePoint

Update enum

​ExponentTranchingMarketReturnModel

​TrancheReturnModel

​UtilizationGuidedCurveParams

​PiecewiseLinearCurveParams

​PiecewiseLinearCurvePoint

​Update enum

ExponentTranchingMarketReturnModel

TrancheReturnModel

UtilizationGuidedCurveParams

PiecewiseLinearCurveParams

PiecewiseLinearCurvePoint

Update enum