Upgrade cUSDC Interest Rate Model
01Summary
Update cUSDC interest rate model to the new LegacyJumpRateModelV2 with standardized parameters matching cDAI and cUSDT (0% base rate, 4% at 80% kink, 25% at 100% utilization), and pay Arr00 a 622 SAI bounty (~$1200) for development work.
- Type
- contract upgrade
- Funding
- $1200
Key changes
- Replace cUSDC interest rate model with LegacyJumpRateModelV2(high)
- Reduce base rate from 2% to 0%(high)
- Introduce kink mechanism at 80% utilization with 4% borrow rate(high)
- Increase borrow rate at 100% utilization from 12.25% to 25%(high)
- Set model owner to Timelock (0x6d903f6003cca6255D85CcA4D3B5E5146dC33925)(medium)
- Pay 622 SAI (~$1200) bounty from reserves to Arr00 (0x2B384212EDc04Ae8bB41738D05BA20E33277bf33)(low)
Notable concerns
- Interest rate model code has not been professionally audited due to simplicity of refactorization
- Model represents significant changes to borrow rate dynamics that may affect user borrowing costs
Generated by Kvorum
02Description
Upgrade cUSDC Interest Rate Model
Summary
Recently, Dharma built, tested, and deployed a new upgradable interest rate model contract for cDAI based on the new JumpRateModelV2. Shortly thereafter, Arr00 proposed an update to the cUSDT interest rate model that followed the new cDAI architecture.
This proposal updates the cUSDC interest rate model to a recently deployed LegacyJumpRateModelV2 with the same parameters as the current cDAI and cUSDT interest rate models:
- 0% base rate (current 2%)
- 4% borrow rate at kink (current no kink)
- Kink at 80% utilization (current no kink)
- 25% borrow rate at 100% utilization (current 12.25%)
- Owner is Timelock (0x6d903f6003cca6255D85CcA4D3B5E5146dC33925)
This proposal completes the effort of setting a standardized interest rate model for all stablecoins on Compound.
The new LegacyJumpRateModelV2 is a simple refactorization of existing code and has been tested using fork simulations. The code has not been audited professionally due to the simplicity of the changes made.
This contract was written, tested, and deployed by Arr00 and reviewed by Dharma. The proposal comes from Dharma as Arr00 does not (yet!) have sufficient COMP delegation.
The last two actions take 622 Sai (currently valued at $1200) from reserves and transfer them to Arr00 as a bounty for his work on this proposal.
Graph of proposed Interest Rate Model
New LegacyJumpRateModelV2
GitHub PR
Discussion
03Mismatch analysis
I compared each decoded action to the corresponding claim in the description. Action 0 targets the cUSDC cToken contract and sets its interest rate model to the exact address referenced in the description and linked Etherscan/PR, matching the claimed upgrade. The specific numeric parameters (0% base, 4% at kink, 80% kink, 25% at 100%) are encoded inside the new model contract itself and not independently verifiable from the calldata beyond the contract address, so I could not directly flag any parameter mismatch — the calldata is consistent with the described deployment. Actions 1 and 2 correspond precisely to the described 'last two actions': reducing cSAI reserves by 622 Sai and transferring the identical 622 Sai amount to a recipient address, which aligns with the stated bounty payment to Arr00. No value, target, or omission discrepancies were found between the prose and the decoded actions. Confidence is high because the addresses, amounts, and action count align well with the narrative, and no unexplained or extra actions are present in the calldata.
Generated by Kvorum
04Actions
- Target
- 0x39aa…7563
- Value
- 0 wei
- Function
- _setInterestRateModel(address)
- Arguments
{ "0": "0xD8EC56013EA119E7181d231E5048f90fBbe753c0" }- Calldata
- Target
- 0xf5dc…44dc
- Value
- 0 wei
- Function
- _reduceReserves(uint256)
- Arguments
{ "0": "622000000000000000000" }- Calldata
- Target
- 0x89d2…0359
- Value
- 0 wei
- Function
- transfer(address,uint256)
- Arguments
{ "0": "0x2B384212EDc04Ae8bB41738D05BA20E33277bf33", "1": "622000000000000000000" }- Calldata
05Tally
Summed from votes
06Voters
No votes recorded yet.
07Forum
- Proposal 23: Update cUSDC interest rate model ↗discourse · high confidence
Arguments for
- Standardizing cUSDC interest rate model with DAI and USDT completes stablecoin alignment on Compound.— arr00
- The new LegacyJumpRateModelV2 enables legacy cTokens like cUSDC to use the same proven logic as newer tokens.— arr00
Arguments against
None surfaced.
Notable participants
- arr00Proposer who designed the upgrade and wrote the LegacyJumpRateModelV2 contract.
Generated by Kvorum
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