Does CurveUSD charge any fees?

In CurveUSD protocol, there are two types of fees users can potentially be exposed to: 1. Borrowing fees (dynamic). 2. Fees/losses during liquidations (both soft LINK and hard liquidations LINK).

Borrowing fees

CurveUSD has a dynamic borrow rate implemented for each market (collateral asset).

The rate adjusts depending on a Peg Keeper contract's debt during the process of keeping the $crvUSD at $1. If the Peg Keeper has burned all uncollateralized $crvUSD (zero debt), and the price of $crvUSD is still below $1, the borrow rates increase rapidly.

Formula: rate = rate0 * exp(-(p - 1) / sigma) * exp(-peg_keeper_debt / (total_debt * peg_keeper_target_fraction))

Formula interpretation: - when the $crvUSD price goes lower, the rate goes higher, and vice versa. - when Peg Keeper's debt goes lower, the rate goes higher, and vice versa.

Soft liquidation losses

During soft liquidations the collateral is sold at a slightly lower price compared to the market price as an incentive for arbitrage bots, causing users to experience certain losses.

Soft liquidation losses increase as the number of price swings within the bands increases. Choosing a bigger number of bands gives you wider price range for liquidation, but increases chances of higher loss during soft liquidations (and gas costs).

Hard liquidation losses

The hard liquidation fees are variable.

If the position is fully liquidated, the liquidators gain all the collateral by paying 100% debt back, and get a liquidation discount (currently set to 6%).

In case of partial liquidation, there is no discount and users are not experiencing the loss by giving up the extra margin (over-collatearization).