Margin (Futures)
In futures trading, margin is the good-faith deposit required to open and maintain a position, functioning as a performance bond rather than a down payment, with the CME Clearing House setting initial and maintenance margin levels for each contract.
Futures margin is fundamentally different from margin in the stock market. When a stock investor buys on margin, they are borrowing money from their broker to purchase shares, paying interest on the borrowed amount. Futures margin involves no borrowing and no interest — it is simply collateral deposited to guarantee that the trader can meet daily settlement obligations. Futures positions are fully leveraged not because capital is borrowed but because only a fraction of the contract's notional value is required as collateral.
The CME Clearing House sets two margin levels for each contract. Initial margin is the minimum deposit required to open a new position. Maintenance margin is the minimum balance that must be maintained after daily P&L is applied. If mark-to-market losses cause an account balance to fall below the maintenance margin level, the broker issues a margin call requiring the trader to deposit additional funds — typically to restore the account to the initial margin level — or close positions.
Margin requirements are calibrated by the exchange using SPAN (Standard Portfolio Analysis of Risk), a system developed by the CME that calculates the maximum expected one-day loss for a portfolio across a range of price scenarios and volatility outcomes. During periods of high market volatility, the CME will increase margin requirements to account for the elevated risk of extreme price moves. These increases can force traders to deposit additional capital or reduce positions during exactly the conditions when doing so is most painful.
For the E-mini S&P 500 (ES), initial margin has historically ranged from roughly $12,000 to $20,000 per contract depending on volatility conditions, while maintenance margin is set somewhat lower. For Micro E-mini contracts, requirements are one-tenth those amounts, consistent with the smaller contract size.
Meeting a margin call promptly is not optional. Futures commission merchants (FCMs) are authorized to liquidate client positions without notice if margin calls are not met, and failure to maintain adequate margin can result in account termination and legal liability for any remaining deficits.