Maintenance Margin
Maintenance margin is the minimum equity balance that must be maintained in a margin account holding futures or leveraged positions; if the account equity falls below this threshold due to adverse price moves, a margin call is issued requiring the account to be replenished to the initial margin level.
Key takeaways
- Maintenance margin is set below initial margin (typically 75–80% of initial margin for futures), providing a buffer that allows for minor adverse price moves before a margin call is triggered.
- When account equity falls below maintenance margin, the holder receives a margin call requiring deposit of variation margin to restore the account to the initial margin level—not merely to the maintenance level.
- Futures exchanges and clearinghouses set margin levels based on the volatility of the underlying contract, adjusted regularly (often daily) to reflect changing market conditions.
- Failure to meet a margin call within the specified timeframe (often by the next business morning) gives the broker the right to liquidate positions at prevailing market prices.
- In the OTC derivatives market, maintenance margin requirements are specified in the Credit Support Annex (CSA) of the ISDA master agreement, governing collateral thresholds and minimum transfer amounts.
Explanation
Maintenance margin is a core risk management mechanism in futures and leveraged derivatives markets, designed to protect the clearinghouse and counterparties from credit exposure arising from adverse price movements. The margin system ensures that each position in the futures market is marked to market daily, with any loss immediately transferred from the losing party to the winning party through the variation margin settlement process. Maintenance margin represents the floor equity level below which the clearinghouse determines the credit risk has become unacceptable.
The relationship between initial and maintenance margin is a deliberate design feature. Initial margin—the deposit required when a position is first established—provides a cushion reflecting the expected maximum daily price move with high confidence (typically covering 99% of one-day price moves). Maintenance margin is set somewhat lower, usually at 75–80% of initial margin, to allow traders to sustain minor adverse moves without being forced to post additional collateral. This buffer reduces the operational burden of continuous variation in margin requirements while maintaining effective credit risk management. Only when cumulative losses erode account equity below the maintenance threshold—indicating a sustained adverse move—is a margin call issued.
The margin call process is operationally well-defined in futures markets. When daily mark-to-market settlement reduces a customer's account below the maintenance margin level, the broker sends a margin call requiring the customer to deposit sufficient funds to restore the account to its initial margin level (not merely to the maintenance level). This restoration requirement can be significantly larger than the shortfall—for example, if initial margin is $10,000, maintenance margin is $7,500, and account equity has fallen to $7,000, the margin call requires a deposit of $3,000 (not merely $500) to bring the account back to $10,000. This feature prevents accounts from hovering just above the maintenance threshold, requiring a meaningful equity buffer restoration.
Exchanges and clearinghouses review margin levels regularly, typically using SPAN (Standard Portfolio Analysis of Risk) methodology for futures. SPAN calculates margin requirements by simulating the portfolio's gain and loss under 16 price and volatility scenarios, taking the worst-case scenario as the margin requirement and allowing offsets for correlated positions. When market volatility spikes—as occurred in March 2020, March 2022, and other stress periods—exchanges raise margin requirements sharply, sometimes doubling them overnight. This procyclical behavior, while necessary from a credit risk perspective, amplifies market stress by forcing levered participants to either post more collateral or liquidate positions, contributing to forced selling cascades.
For institutional investors including hedge funds, maintenance margin management is part of daily liquidity risk management. Funds must maintain sufficient cash or highly liquid securities to meet potential margin calls across their entire futures book, sized for realistic adverse scenarios. A fund running a $1 billion futures portfolio with average leverage of 3× must be prepared for margin calls that could approach 5–10% of notional (approximately $15–30 million) in a one-day stress scenario. Liquidity buffers, revolving credit facilities, and portfolio stress-testing against historical margin call scenarios (e.g., 1987, 2008, 2020) are standard risk management practices.
Formula
Margin Call Trigger: Account Equity < Maintenance Margin; Margin Call Amount = Initial Margin − Current Account Equity
Example
A commodity trading advisor (CTA) holds 100 WTI crude oil futures contracts (1,000 barrels each) as part of a long trend-following position. The initial margin per contract is $6,500 (set by CME), so total initial margin = 100 × $6,500 = $650,000. The maintenance margin is $5,500 per contract, total = $550,000. The account begins with $650,000 equity. Over three days, oil prices fall: Day 1: −$1.00/barrel, loss = 100 × 1,000 × $1.00 = $100,000; account equity = $550,000 (exactly at maintenance margin, no call yet). Day 2: −$0.20/barrel additional loss = $20,000; account equity = $530,000, which is below maintenance margin of $550,000. The broker issues a margin call requiring restoration to the $650,000 initial margin level. The CTA must deposit $120,000 ($650,000 − $530,000) by the next business morning, or the broker will liquidate a portion of the position to reduce margin requirements to a level supportable by remaining equity.
Related terms
Call Option Credit Risk Equity Floor Initial Margin Leverage Liquidity Liquidity Risk Margin Margin Call Mark To Market Option Pricing Model