♻️Liquidations

The health of Exactly's Protocol depends on the 'health' of the loans within the system, also known as the 'health factor'. When the health factor of an account's total loans is below 1, anyone can make a liquidate() call to the Market contract, paying back part of the debt owed, and receiving discounted collateral in return (also known as the liquidation bonus as previously seen here).

This incentivizes third parties to participate in the solvency of the overall protocol by acting in their interest (to receive the discounted collateral) and, as a result, ensure loans are sufficiently collateralized.

Instructions

In order to know whether an account can be liquidated or not, the accountLiquidity function in the Auditor contract can be called.

As for the marketToSimulate parameter, the address zero should be passed, and zero (0) should also be sent as withdrawAmount.

accountLiquidity

function accountLiquidity(address account, contract Market marketToSimulate, uint256 withdrawAmount) external view returns (uint256 sumCollateral, uint256 sumDebtPlusEffects)

Parameters

Name	Type	Description
account	address	account in which the liquidity will be calculated.
marketToSimulate	contract Market	market in which to simulate withdraw operation.
withdrawAmount	uint256	amount to simulate as withdraw.

Returns

Name	Type	Description
sumCollateral	uint256	sum of all collateral, already multiplied by each adjust factor (denominated in base).
sumDebtPlusEffects	uint256	sum of all debt divided by adjust factor considering withdrawal (denominated in base).

This function will return the total adjusted collateral and debt of the account. Then the collateral can be divided by the debt to get the health factor.

If its value is lower than 1, then the liquidate function will not revert when being called for that user.

Other more efficient ways of checking for account positions require monitoring block-to-block transactions. This is the approach followed by our open-source and team-driven bot.

Once there's an account opened to be liquidated, the liquidate function can be called to successfully repay the debt of that user and seize a portion of its collateral with a discount.

The function expects and returns the following arguments:

liquidate

function liquidate(address borrower, uint256 maxAssets, contract Market seizeMarket) external nonpayable returns (uint256 repaidAssets)

Parameters

Name	Type	Description
borrower	address	wallet that has an outstanding debt across fixed and variable pools.
maxAssets	uint256	maximum amount of debt that the liquidator is willing to accept. (it can be less)
seizeMarket	contract Market	market from which the collateral will be seized to give the liquidator.

Returns

Name	Type	Description
repaidAssets	uint256	actual amount repaid.

It's important to highlight that maxAssets should also include an extra bonus that the variable pool of the Market will keep that the debt is being repaid.

Health Factor

The health factor is calculated from the user's collateral balance (in ETH) multiplied by each asset's adjust factor divided by the user's debt which is also divided by this adjust factor.

For example: given an ETH adjusted factor of 0.84, a deposit of 100 ETH and borrow of 50 ETH:

The adjusted collateral will be equal to 100*0.84 = 84.00

The adjusted debt will be equal to 50/0.84 = 59.52

So the health factor will be equal to 84.00/59.52 = 1.41

Below a health factor of 1, the user will be considered with shortfall and open to liquidation.