Maintenance Margin

Maintenance margin is the minimum equity a leveraged position must keep before the venue becomes entitled to close it. It is distinct from initial margin, which is what must be posted to open a position: initial is a threshold you cross once, maintenance is a floor you must stay above for as long as the position is open, and touching it triggers a margin call or an outright liquidation depending on the platform's rules. The level is set by the venue rather than by any protocol. It differs by asset and frequently by position size, and it can be changed — including while a position is open, which is a risk entirely separate from the market moving against you. It is also measured against a reference price the venue selects, often a mark price rather than the last traded price, so a position can be closed at a level that never appears in that venue's own trade history.