Maintenance margin is the minimum amount of equity that must be maintained in a margin account to keep leveraged positions open. When account equity falls below the maintenance margin requirement, a margin call is triggered, requiring additional funds or position closure. Maintenance margin levels are typically lower than initial margin requirements but serve as crucial risk management safeguards.

Maintenance margin requirements vary by instrument type, volatility levels, and broker policies, with more volatile assets requiring higher maintenance levels. During periods of increased market volatility, maintenance margin requirements may be raised to reflect higher risk levels. Understanding maintenance margin helps traders manage leverage and avoid forced liquidations that could realize unnecessary losses.

Real-world example: A futures trader holds crude oil contracts requiring $3,500 maintenance margin per contract, meaning account equity must stay above this level or face margin calls requiring immediate deposit of funds or position closure.