Net rates as DEX trading fee APY changes
Same collateral, debt and base rates — sweeping the pool's trading fee APY from 0% to 10%. Watch net debt cost cross zero.
| Trading fee APY | Net collateral APY | Net debt APY (cost) | Net APY on equity |
|---|
Why "get paid to borrow" is a real, documented state
On a standard money market (Aave, Compound), your debt only ever costs you the borrow rate — there is no mechanism for it to do anything else. Fluid's Smart Debt makes the debt position itself an LP share in a Fluid DEX pool, so it earns a real cut of swap volume the entire time it's outstanding. Fluid's own materials describe borrow rates commonly sitting in the 3-5% band while, in high-volume periods, some borrowers effectively pay close to 0% or get paid to hold debt — because the trading fee income line item is large enough to flip the net sign. See Uniswap v4 hooks fee calculator for the mechanics of how a pool's trading fee rate itself gets set.
The math behind Smart Debt and Smart Collateral
Fluid's architecture (the "Liquidity Layer" plus "Fluid DEX") lets a single LP position serve double duty. A Smart Collateral position is a DEX LP share deposited as collateral: it keeps earning trading fees from swaps routed through that pool while simultaneously backing a loan, so its net effective yield is net_collateral_APY = base_supply_APY + trading_fee_APY — strictly additive, since collateral only ever earns. A Smart Debt position flips the same mechanism onto the borrow side: your debt is minted as an LP share too, so the fees it earns are netted directly against what you owe, giving net_debt_APY = base_borrow_APY − trading_fee_APY. Unlike the collateral side, this can go negative — once trading_fee_APY exceeds base_borrow_APY, the borrower is paid, not charged.
Putting both sides together, the overall return on your actual equity (collateral minus debt) is net_equity_APY = (collateral × net_collateral_APY − debt × net_debt_APY) / (collateral − debt). With $10,000 collateral, $6,000 debt, a 3% base supply rate, 5% base borrow rate and a 4% pool trading fee APY on both legs, net collateral APY is 3%+4%=7%, net debt APY is 5%−4%=1%, and equity of $4,000 earns (10,000×7% − 6,000×1%) = $640/yr, or 16% on equity — versus a flat 0% on the exact same position with neither Smart feature switched on ($10,000×3% − $6,000×5% = $0). That 16-point gap is entirely the DEX fee layer; it costs nothing extra in leverage and adds no new liquidation risk on the interest-rate side (though the LP share itself carries ordinary impermanent-loss exposure the way any DEX position does).