What is Maintenance Margin?

Maintenance margin is the minimum amount of equity (collateral) a position must maintain to stay open. When your equity drops to the maintenance-margin level — because the mark price moved against you — the position is liquidated.

It is usually expressed as a percentage of notional (e.g. 0.5%). Initial margin is what you post to open; maintenance margin is the lower threshold you must not breach to keep it open.

Lower maintenance margin means more leverage headroom but a thinner buffer before liquidation. Each venue sets its own tiered schedule, so the same position can be safer on one exchange than another.