Maintenance margin is the minimum collateral support required to keep a margined position or account within its risk limits. It is distinct from initial margin, which determines the resources needed to establish exposure.
How the requirement changes
A venue may calculate maintenance margin from position value and a specified rate, with tier adjustments or other deductions. Larger positions can fall into higher risk tiers. The requirement may also change as prices move, even when the number of contracts stays constant.
The maintenance margin rate is a calculation input; the maintenance margin amount is the resulting collateral requirement. Neither should be confused with an account’s displayed risk ratio.
Why the remaining buffer matters
Losses reduce equity available to meet the requirement. Funding payments, collateral price changes and other positions may also affect the buffer, depending on margin mode.
If the required support is no longer available, the venue may reduce or liquidate exposure under its rules. This can happen before the entire original deposit is lost, and a prior margin call is not guaranteed. A position’s displayed liquidation price may be only an estimate when risk is assessed across an account.