BitMEX supports different margin modes: Single Asset Margin and Multi Asset Margin. Each contract has a defined Settlement Currency which is used to pay/receive realise profit and loss, fees and funding. There are currently two Settlement Currencies : Bitcoin (XBT) and Tether (USDT).

Single Asset Margin

In Single Asset Margin mode, opening a position requires margin to be deposited that matches the Settlement Currency of the contract. Accounts are required to have a positive excess margin balance in each Settlement Currency at all times, or else they will be liquidated.

Multi Asset Margin

In Multi Asset Margin mode, margin balances in a selection of currencies count towards an account-level Multi Asset Margin margin balance. Each of these can be used to support margin requirements for contracts settled in either USDT or XBT, but haircuts are applied to the value of the margin currencies to reflect the additional risk BitMEX is undertaking by supporting margin requirements with different currencies.

The table below shows the current Margin currencies and their haircuts:

	USDT Margin	SOL Margin	ETH Margin	XBT Margin	USDC Margin
USDT Settlement	0%	5%	5%	2%	1%
XBT Settlement	2%	5%	4%	0%	2%

Some users may be more familiar with the term Collateral Value Ratio which is usually defined as (1 - Haircut).

Because the Haircut varies by Margin Currency and Settlement Currency, we optimise your available Margin Currency balances against your margin requirements. If they do not meet your margin requirements you will be liquidated.

How do I turn on Multi Asset Margin?

BitMEX supports Multi Asset Margin on an account-by-account basis. In the subaccounts settings, you can opt individual subaccounts in and out of Multi Asset Margin. This functionality is also available via API.

Does Multi Asset Margin support all products and features on BitMEX?

Multi Asset Margin is compatible with most existing features on BitMEX.

Currently Multi Asset Margin accounts do not support isolated margin or prediction futures positions, if an account has open positions in either contract type it will be impossible to enable Multi Asset Margin until the positions are closed.

What happens when I receive fees, funding? How do I realise a profit?

Any amounts due to your account for fee rebates, funding or realised profit will be paid in the Settlement currency for that contract, regardless of the margin currencies used. These payments will automatically add to your Available Margin for that Multi Asset Margin account.

What happens when I pay fees, funding? How do I realise a loss?

Fees are charged in the Settlement currency of the contract (so a USDT fee for ETHUSDT, and a XBT fee for XBTUSD for example). In Multi Asset Margin mode, if you don’t have enough of the Settlement currency in your account, we will take from your other Margin currencies to cover the fee.

Funding fees are also paid in the settlement currency for a contract. Similar to trading fees, when funding fees are taken from your account, if you do not have sufficient available Settlement currency, then other Margin currencies will be taken from your margin and converted into the settlement currency to cover the funding fee.

In the same way, when you realise a loss, if you have insufficient Settlement currency to cover it, we will take the required amount from your other Margin currencies.

In all of the cases above, you will see a spot conversion transaction in your transaction history that converts your existing margin currency into the required amount of Settlement currency. These conversions will occur at the index prices with haircuts applied.

Can my balances go negative?

Your individual settlement currency margin balances may go negative if they have unrealised losses and supported by other margin currencies

Your total excess margin balance across all margin currencies needs to remain positive at all times.

There is a per-account limit to the negative margin balance in each settlement currency that can be supported by other margin currencies. These limits are:

• 2 XBT
• 100,000 USDT

If your negative margin balance exceeds this, some of your margin will be converted to the negative balance currency to bring you below this limit.

There is also a global negative margin balance limit across all MAM-enabled accounts across the platform. If these negative margin balances are exceeded across all MAM-enabled accounts, each account with a negative balance will have some margin converted to the negative balance currency to bring accounts below this limit globally.

Can I trade Spot with Margin Currencies in a Multi Asset Margin account?

You can trade any of the available currencies in your account, up to the Withdrawable Amount (shown in your Wallet section under the Balances tab) for that currency. For example, if you have 2000 USDC and 1 ETH in your spot account but your withdrawable amount of USDC is only 1000 and your withdrawable amount of ETH is only 0.5 ETH, you will not be able to sell more than your withdrawable amount of either currency.

Examples

Example 1

User has:

Margin Requirement:
    10,000 USDT
    0.2 XBT
Margin Balances:
    12,000 USDT
    20,000 USDC
    2 ETH
    0.1 XBT
And the index prices are:
    .BUSDC: 1.0
    .BUSDT: 1.0
    .BETH: 3,000
    .BXBT: 120,000

USDT requirements come out of margin balances running from left to right on the diagram above, while XBT requirements come out of margin balances by running from right to left. If the requirement bars meet in the middle, an account is in liquidation.

Looking at USDT requirements first, we see that the USDT margin balance of 12,000 completely covers the USDT requirements of 10,000 USDT. We take these out, and are left with:

Margin Requirement:
    0.2 XBT
Margin Balances:
    2,000 USDT
    20,000 USDC
    2 ETH
    0.1 XBT

For the XBT requirement of 0.2 XBT, we initially credit the 0.1 XBT of margin balance, which leaves another 0.1 XBT of requirement to be covered by the other coins.

Next we will take the ETH, which is second-from-the-right. ETH has a margin cover power of 95% in XBT. So we convert it into XBT terms by multiplying the ratio of the index prices by 95%:

ETH_balance * 95% * .BETH / .BXBT

= 2 * 0.95 * 3000 / 120000
= 0.0475 XBT

We take this away from the 0.1 XBT of requirement, which leaves us with:

Margin Requirement:
    0.0525 XBT
Margin Balances:
    2,000 USDT
    20,000 USDC

Next on the list is USDC, so we will need to take some USDC to cover the 0.0525 XBT of requirement. USDC also has a margin cover power of 95% in XBT, so the amount of USDC required to fully cover the requirement is:

0.0525 * .BXBT / (.BUSDC * 95%)
= 0.0525 * 120000 / (1 * 0.95)
= 6631.578947

So the USDC balance is sufficient to cover the remaining XBT requirement. Since we have margin balance left over, the account is safe and we are not in liquidation.

The “left over” portion of the margin is:

2,000 USDT
13,368.42 USDC

From this we can also calculate the available margin in both USDT and XBT terms (which tells us how much more requirement of positions we can open in either currency):

USDT has a margin cover power of 100% in USDT and 95% in XBT USDC has a margin cover power of 98% in USDT and 95% in XBT

So our excess margin in USDT terms is:

2000 * 100% + 13368.42 * 98% * (.BUSDC / .BUSDT)
= 2000 + 13368.42 * 0.98 * (1.0/1.0)
= 15101.05 USDT

Our excess margin in XBT terms is:

2000 * 95% * (.BUSDT / .BXBT) + 13368.42 * 95% * (.BUSDC / .BXBT)
= 2000 * 0.95 * (1/120,000) + 13368.42 * 0.95 * (1/120000)
= 0.12166666 XBT

Example 2

If the user in the previous example had these margin requirements instead…

User has:

Margin Requirement:
    15,000 USDT
    0.3 XBT
Margin Balances:
    12,000 USDT
    20,000 USDC
    2 ETH
    0.1 XBT
And the index prices are:
    .BUSDC: 1.0
    .BUSDT: 1.0
    .BETH: 3,000
    .BXBT: 120,000

This time, there is not enough USDT margin balance to cover the USDT margin requirements. The remaining 3,000 USDT of requirement is covered by 3000 / (0.98 * 1.0 / 1.0) = 3,061.224489 of USDC.

To cover the 0.3 XBT, this leaves the following converted into XBT:

16,958 USDC = 16,958 * 0.95 * (1.0 / 120,000) = 0.13425 XBT
2 ETH = 2.0 * 0.95 * (3,000 / 120,000) = 0.0475 XBT
0.1 XBT

Unfortunately, summing these gives 0.13425 + 0.0475 + 0.1 = 0.282 XBT, which is lower than the 0.3 XBT requirement. This means the excess margin for the account is negative and the account will be liquidated.