Collateral and yield - Matocard

How collateral is held

When a top-up is credited, its AUSD goes into an ERC-4626 yield vault, and the vault shares are recorded as your collateral. Their value is read with the vault’s own convertToAssets, so no outside price oracle is involved.

	Testnet	Mainnet (planned)
Vault	MockEarnAUSD	earnAUSD
Yield source	Whatever the operator pays in, to show the mechanism	Trading strategies (basis trade, delta-neutral)
Withdrawals	Instant	Can queue up to 72 hours

The yield fee

Borrowing is interest-free. Instead, the protocol keeps 20% (yieldFeeBps = 2000) of the yield your collateral earns. It is charged when collateral leaves or changes, and it is what lenders earn for funding the line. Your collateral value, and so your limit, is always shown net of the fee already accrued.

Taking collateral out

withdrawCollateral redeems the vault shares you name and sends you the AUSD, as long as your debt stays within your new, lower limit. With no debt, you can withdraw everything.

If the vault loses value

Your collateral value falls, and your limit falls with it. If you are now over your limit, new draws are blocked, but you are not defaulted for it: default only ever follows a missed due date.