Simple Summary
Gauntlet recommends separating the interest rate curves of the Optimism USDC and USDT Comets so that each market's rates can be tuned to its own level of demand. Both Comets currently share an identical interest rate model, but their demand profiles have diverged. USDC is running at its 90% kink, while USDT sits below it at 82%. We propose increasing the borrow and supply slopes (low and high) on cUSDCv3 by 5% and decreasing them on cUSDTv3 by 5%.
Motivation
| Comet | Supply | Borrow | Utilization | Supply APR | Borrow APR |
|---|
| cUSDCv3 | $1.55M | $1.40M | 90.0% | 3.34% | 4.11% |
| cUSDTv3 | $1.54M | $1.27M | 82.2% | 2.96% | 3.91% |
Data as of September 30, 2026.
USDC is at the kink with steady borrow demand. Raising the slopes rewards suppliers more for providing liquidity. It also makes borrowing more expensive, which helps keep utilization at or below the kink and protects withdrawal liquidity.
USDT has room below the kink. Lowering the slopes reduces the cost of borrowing, which should draw in borrow demand and move utilization toward the kink.
Specification
Only the borrow and supply slopes change. The borrow base rate (3%), supply base rate (0%), and both kinks (90%) are unchanged.
| Parameter | Current (both) | Proposed cUSDCv3 | Proposed cUSDTv3 |
|---|
| Borrow Slope Low | 1.1111% | 1.1667% | 1.0555% |
| Borrow Slope High | 360% | 378% | 342% |
| Supply Slope Low | 3.60% | 3.78% | 3.42% |
| Supply Slope High | 319.6% | 335.58% | 303.62% |
Proposal Actions
The proposal sends one cross-chain message from Ethereum mainnet to Optimism via the Optimism bridge. For each of cUSDCv3 (0x2e44e174f7d53f0212823acc11c01a11d58c5bcb) and cUSDTv3 (0x995e394b8b2437ac8ce61ee0bc610d617962b214), it calls:
Configurator.setBorrowPerYearInterestRateSlopeLow(comet, newSlope)Configurator.setBorrowPerYearInterestRateSlopeHigh(comet, newSlope)Configurator.setSupplyPerYearInterestRateSlopeLow(comet, newSlope)Configurator.setSupplyPerYearInterestRateSlopeHigh(comet, newSlope)CometProxyAdmin.deployAndUpgradeTo(configurator, comet)
User Impact
| Comet | Supply APR at current utilization (current / proposed) | Borrow APR at current utilization (current / proposed) |
|---|
| cUSDCv3 | 3.34% / 3.51% | 4.11% / 4.17% |
| cUSDTv3 | 2.96% / 2.81% | 3.91% / 3.87% |
- Suppliers. Because the supply base rate is 0, supply APRs move by the full 5% at every utilization level. USDC suppliers earn more and USDT suppliers earn less.
- Borrowers. The borrow base rate is unchanged, so below the kink borrow APRs move by about 1.25%. Above the kink the slope high change applies in full. For USDC, each point of utilization above 90% adds roughly 3.78% to the borrow APR, compared with 3.60% today.
- Reserves. At current utilization, the USDC spread narrows and the USDT spread widens, so combined reserve accrual across the two Comets stays roughly flat. Gauntlet will monitor USDC utilization after the change and will recommend further adjustments if reserve accrual turns unfavorable.
For the full analysis and risk considerations, see the forum post: [Gauntlet] Optimism cUSDCv3 and cUSDTv3 Interest Rate Curve Adjustments
