Multicollateral Margin

Last updated: Jun 16, 2026

Use supported assets such as USDT and WETH to fund a single cross-margin perps account. This page is the conceptual overview. For step-by-step collateral operations, see Depositing Collateral and Withdrawing Collateral.

Overview

Synthetix supports unified margin. All supported collateral types in a subaccount contribute to that subaccount's account value, while perpetual markets remain quoted and settled in USDT.

You can:

Deposit USDT or supported non-USDT collateral such as WETH.
Trade USDT-settled markets using your combined collateral value.
Withdraw each asset separately, subject to margin, balance, and debt limits.
Swap non-USDT collateral into USDT when your account has USDT debt.

Trading fees, funding, and realized PnL settle into the USDT balance. If you hold mostly non-USDT collateral, your USDT balance can go negative during normal trading.

How it works

Deposit supported collateral into a subaccount.
The account receives margin credit based on each asset's value. USDT counts at face value; non-USDT collateral contributes its haircut-adjusted value.
Open or manage positions in USDT-settled markets.
Fees, funding, and realized PnL update the USDT balance.
If the USDT balance becomes debt, repay voluntarily with Swap or reduce risk before forced auto-exchange becomes possible.

USDT debt

Your USDT balance can go negative during normal trading:

Trading fees
Funding payments
Realized losses when positions are reduced or closed

A negative USDT balance is only treated as debt after positive unrealized PnL is considered. A winning open position can temporarily offset negative USDT.

Situation	What happens
Open positions, negative USDT, positive UPNL covers it	Allowed - not treated as debt. Swap not available.
Open positions, negative USDT, UPNL does not fully cover	USDT debt exists - backed by collateral. LTV caps and Swap apply.
Close positions with USDT debt remaining	Debt is not auto-repaid. Use Swap voluntarily, or forced auto-exchange if debt exceeds allowed limit.
Debt exceeds allowed limit	Forced auto-exchange can convert non-USDT collateral to USDT.
Winning position, negative USDT	Positive UPNL can support USDT withdrawals and may eliminate effective debt.

Swap (voluntary collateral exchange)

Use Swap on any non-USDT balance row to convert collateral into USDT.

Swap is available when you have USDT debt: negative USDT that is not fully covered by positive unrealized PnL. If USDT shows negative but a winning open position backs it, Swap may be unavailable because there is no effective debt to repay.

How it works:

Select the source asset and amount.
Review the estimated USDT received after fees.
Confirm. Collateral is sold and you receive USDT minus a fee.

Swapping to repay debt improves account health and can restore withdrawable margin when debt or LTV constraints are limiting withdrawals.

Auto-exchange

Auto-exchange converts non-USDT collateral to USDT without manual action. It protects the protocol and keeps accounts solvent.

When forced auto-exchange runs

Forced auto-exchange runs automatically during account health checks when your USDT debt exceeds your allowed debt limit.

Allowed debt is the lower of:

Sum of (each non-USDT asset's Collateral Value x its LLTV)
Your tier's Max Borrow

When breached, the system sells non-USDT collateral until debt is back within limits.

Asset selection

The system sells assets with the lowest haircut first (deterministic tie-break by asset name when haircuts are equal). Forced exchanges use a higher fee rate than voluntary Swap.

LLTV and LTV

Term	Meaning
LTV (Loan-to-Value)	Your current USDT debt divided by total adjusted non-USDT collateral value. Shown per asset row when you have debt.
LLTV (Liquidation LTV)	Maximum LTV before forced auto-exchange for that asset. Shown in the balances table.
Max Borrow	Maximum USDT debt allowed for your tier.

If LTV reaches LLTV, collateral is auto-exchanged until LTV returns to zero.

Example (WETH, LLTV 80%): If your debt is 80% or more of your non-USDT collateral value, WETH may be sold to USDT automatically at best available prices minus the forced-exchange fee.

Account health checklist

When using non-USDT collateral, monitor:

Collateral Value - haircut-adjusted value that counts toward margin.
Available Margin - margin available to open or increase positions.
Unrealized PnL - can offset negative USDT while positions are open.
LTV and LLTV - debt usage versus debt limits.
Max Borrow - the tier-based cap on total USDT debt.