Lend
Reserves
Each asset has one reserve. Suppliers deposit into it and earn interest, and every borrow in Comet draws from it: a plain borrow, a leveraged range or a perp.
Supplying
A deposit into a reserve is recorded as shares of that reserve. The value of a share rises as borrowers pay interest, so your balance grows without any claim step. You can withdraw at any time, up to the reserve’s unborrowed balance.
Deposits sit in your margin account, where they also count as collateral.
Borrowing
A plain borrow sends tokens from a reserve to your wallet, against your account’s deposits and up to its borrow limit. A borrow has no term: it stays open while your account’s health holds, and you can repay any part of it at any time.
Leveraged ranges and perps borrow from the same reserves, inside the transaction that opens them.
How interest accrues
A reserve tracks one number for all of its borrowers, the borrow index. Each time the reserve is touched, the index grows by the interest for the slots since the last touch.
- rate
- the borrow rate at the reserve’s current utilization
- Δt
- time since the last update, as a share of a year
Your debt is the amount you borrowed, scaled by how far the index has moved since. The rate itself comes from the reserve’s utilization; the curve is on Interest rates.
Where borrow interest goes
Borrow interest is split by the reserve factor. Suppliers receive everything outside it, as growth in the value of their shares. The reserve factor goes to the protocol, and 20% of that share accrues to the reserve’s backstop.
| Reserve | To suppliers | Reserve factor |
|---|---|---|
| USDC | 90% | 10% |
| SOL | 85% | 15% |
| JitoSOL | 85% | 15% |