Fee Rates
How Hubble determines the one-time fee for borrowing.
There are two times when users experience fees:

Borrowing Fee

  • at the time of borrowing USDH
At borrowing time, the fee is calculated based on the borrowed amount and is added on top of a user's debt. For example, if a user borrows 100 USDH and the fee rate is 0.5%, then the following occurs:
  • Hubble mints 100 USDH into the borrower's wallet
  • Hubble mints 0.5 USDH into the HBB Stakers' pool
  • The borrower's Hubble account records a debt of 100.5.

Stability Fee

Hubble's Stability Fee serves two purposes:
  • Support USDH's peg
  • Create revenue for USDH stakers
When USDH falls below its peg, the Stability Fee is raised to incentivize user-initiated repayments of USDH loans. When users introduce too much USDH to the market, USDH's price can fall below parity with 1 USD.
By raising the Stability Fee, borrowing USDH becomes more expensive and makes repaying USDH loans a more cost-efficient option. As users acquire USDH from the market to repay their loans, the market supply of USDH contracts and raises prices back to $1.
A portion of the collected Stability Fee is rewarded to users who stake USDH in the USDH Vault, creating a Hubble-native savings rate for USDH.