Summary
We propose listing a USDT Convex leveraged vault on Notional V3 Arbitrum. The vault would allow users to borrow USDT from Notional’s Arbitrum deployment at a fixed or variable rate and LP the proceeds in the Convex boosted Curve USDT/crvUSD pool to earn pool rewards.
Proposal & parameters
We propose listing a USDT leveraged vault using the Convex boosted Curve USDT/crvUSD pool as a strategy. We propose listing that leveraged vault strategy with the following parameters:
| Vault Parameters | Proposed Value |
|---|---|
| LiquidationRate | 1.03 (3%) |
| MinCollateralRatioBPS | 0.14 |
| MaxDevelerageCollateralRatioBPS | 0.26 |
| MaxRequiredAccountCollateralRatioBPS | 1.00 |
| Maximum vault capacity | 2,000,000 USDT |
| Minimum borrow size | 5,000 USDT |
| feeRate5BPS | 20 (100 BPS) |
| ReserveFeeShare | 80% |
| Strategy Parameters | Proposed Value |
|---|---|
| maxPoolShare | 20% |
| oraclePriceDeviationLimitPercent | 1.50% |
By adding this leveraged vault strategy to Notional, the protocol will effectively accept Curve USDT/crvUSD pool tokens as collateral. We propose setting the maximum vault capacity up to 2,000,000 USDC to cap the maximum amount of USDT that can be borrowed from Notional to enter that specific strategy. In practice Notional governors will increase the maximum capacity of the vault in line with demand and USDT liquidity up to the 2,000,000 USDC maximum vault capacity threshold. We propose setting the maximum pool share at 20% such that users won’t be able to enter the vault if the protocol already holds more than 20% of Curve USDT/crvUSD pool tokens.
We propose setting the maximum leverage at 8.1X such that if a user deposits 10,000 USDT, he can at a maximum borrow 71,430 USDT from Notional to LP in the Curve USDT/crvUSD pool. This maximum leverage ratio (minimum collateral ratio) aims to protect the protocol against a large decrease in the pool’s token value. Setting the strategy’s maximum leverage ratio at 8.1X ensures the protocol would be protected against a decrease of -9.7% in the pool’s token value (USDT/crvUSD LP tokens) relative to the vault’s borrow currency (USDT). It’s important to note that the vault’s maximum leverage ratio is set as a precautionary buffer to protect the protocol against a decrease in the value of pool tokens relative to users’ debts.
We propose setting the MaxDeleverageCollateralRatio at 0.26, this implies that a liquidator can lower an account’s leverage ratio to 4.9X if it ever breaches the max leverage ratio of 8.1X. This ratio is set such that an account that gets liquidated will subsequently be able to withstand another large decrease in the strategy token price before becoming eligible for liquidation again thereby lowering the risk of an account being liquidated multiple times in a short period of time.
We propose setting the minimum borrow size at 5,000 USDT and the vault liquidation discount at 3%. These parameters aim to maximize the likelihood of successful liquidations under stressed market conditions (ex: high gas environment). To do so, a liquidator’s revenue from the liquidation discount must be sufficient to cover liquidation expenses (gas cost, slippage, Dex fee, price basis). By setting the minimum borrow size at 5,000 USDT and the liquidation discount at 3%, liquidators will likely receive at a minimum 150 USDT. Based on historical market conditions such a liquidation discount is likely cover a liquidator’s expenses under most scenarios.
We propose setting the leveraged vault fee at 1.0% such that borrowers will pay a 1.0% premium on their borrow rate when entering the vault. We propose setting the reserve fee share at 80% such that 80% of the borrow premiums will go to Notional reserves and 20% are paid to nUSDT holders.
We propose setting the oraclePriceDeviationLimitPercent to 1.50%. The oraclePriceDeviationLimitPercent prevents users from entering or exiting the vault if the implied pool prices deviate from the oracle prices by more than 1.5%. This parameter mitigates oracle attack vectors while being flexible enough to ensure user can enter and exit the vault even if oracle prices slightly deviate from on-chain prices in between updates.
Risks
Oracle
We propose using the Chainlink crvUSD and USDT oracles to check that the implied Curve pool exchange rate is in line with the overall market.
Liquidity
There is a risk that crvUSD liquidity vs USDT decreases over time. In such a situation, it could be the case that it is impossible to flash liquidate an account breaching the Notional’s maximum leverage ratio. By listing this leverage vault Notional implicitly accepts crvUSD as a collateral asset.
The crvUSD liquidity risk can be somewhat mitigated by capping the protocol’s exposure at 20% of the pool and by setting the maximum vault capacity in line with Notional’s USDT liquidity.