Initial vs Maintenance Margin in Futures

The two margin levels, and the dreaded call.

Futures margin requirements sit at the center of how leveraged derivatives actually work. Open a position in an E-mini S&P 500 contract and your broker does not ask for the full notional value of the contract — it asks for a fraction, called the initial margin, as a performance bond. That deposit buys you exposure to the entire contract. As prices move, your account balance moves with them via mark-to-market settlement each day, and if your balance falls below a second, lower threshold — the maintenance margin — you get a margin call. Understanding exactly how those two numbers interact, and what a margin call actually demands, is essential before you touch a leveraged futures account. Pair this with the futures pricing calculator to see how your notional exposure scales with contract size before you put on a position.

What futures margin requirements actually are

Futures margin is not a down payment or a loan in the traditional sense. It is a good-faith deposit — a performance bond held by the clearinghouse to ensure both parties can meet their daily settlement obligations. There are two levels:

• Initial margin is the amount required to open a position. You must have at least this much in your account before the trade executes. It is set by the exchange (via its SPAN or similar risk model) and varies by contract and volatility regime.
• Maintenance margin is a lower floor, typically 75–80% of the initial level, that your account balance must stay above while the position remains open. As long as your equity stays at or above maintenance, no action is required.

The gap between the two is deliberate. It gives the account room to absorb adverse daily moves without triggering a call on every minor fluctuation. What it does not do is let you restore only to maintenance if a call fires — when the balance drops below the maintenance floor, the call requires you to bring the account all the way back to the full initial margin level.

Daily settlement and how the balance moves

Unlike equity positions, futures are not settled at close of the trade — they are settled every single day. At the end of each session, the clearinghouse marks every open position to the settlement price and credits or debits the difference directly to each account. This is daily mark-to-market, and it means gains and losses are realized in cash each night, not just on paper.

Consider a crude oil futures contract (WTI, NYMEX CL) with a contract size of 1,000 barrels. A one-dollar move in crude moves the contract by $1,000. Suppose the exchange sets initial margin at $6,000 and maintenance margin at $4,500 per contract. You buy one contract at $80.00/barrel, depositing $6,000.

Day	Settlement Price	Daily P&L	Account Balance	Action
Open	$80.00	—	$6,000	Position opened
Day 1	$79.20	−$800	$5,200	None — above maintenance
Day 2	$78.40	−$800	$4,400	Margin call triggered
Day 2 (after call)	$78.40	—	$6,000	Deposit $1,600 to restore initial
Day 3	$79.10	+$700	$6,700	None

On Day 2 the balance hits $4,400 — below the $4,500 maintenance floor. The margin call does not ask for $100 to restore the account to $4,500; it demands $1,600 to bring the balance back to the full $6,000 initial margin. That asymmetry catches many new futures traders off guard.

The leverage this creates

With a $6,000 initial margin against a notional of $80,000 (1,000 barrels × $80), the leverage ratio is roughly 13:1. A 1.25% adverse move in crude — just $1 per barrel — consumes $1,000 of a $6,000 deposit, a 16.7% hit to posted collateral. Leverage amplifies gains by the same factor: a $2 move in your favor turns a $12,000 notional gain into a 200% return on the margin deposit, on paper, before the position is closed.

This is the core asymmetry of futures: the capital at risk each day is the full notional swing, but the capital posted is a small fraction of that notional. A trader watching the futures curve drift into deep contango may be tempted to hold a long position for weeks — but each night the mark-to-market arithmetic applies regardless of longer-term conviction. You can be right about the direction and still blow out of the trade because a short-term adverse run exhausts your available margin buffer.

SPAN and portfolio margining

The CME and most major exchanges calculate initial margin using SPAN — the Standard Portfolio Analysis of Risk system. Rather than assigning a fixed dollar amount per contract, SPAN models a portfolio of futures and options across a grid of price and volatility scenarios and sets margin equal to the worst-case loss across that scenario set. The result is that offsetting positions — a long crude and a short heating oil, for example, where the two legs are historically correlated — receive a margin credit because the combined portfolio is less risky than the sum of its parts.

Portfolio margining takes the same logic further. For accounts that hold futures alongside related equity or ETF positions, regulators in some jurisdictions allow the clearinghouse to consider the entire book when computing margin. A long S&P futures hedge against a short equity basket can reduce overall margin requirements materially. Both approaches reward genuine risk reduction rather than punishing each leg in isolation.

Why the call restores to initial, not maintenance

The mechanics of the margin call reflect the clearinghouse's risk management logic. Maintenance margin is calibrated to absorb a typical one-day adverse move. Initial margin is calibrated to absorb a stressed move — a larger buffer that gives the clearinghouse time to liquidate the position if needed. When a balance drops to maintenance, it has already absorbed most of its cushion. Restoring only to maintenance would leave the account one more bad day away from another call. Restoring to initial re-establishes the full buffer, reducing the probability of a cascade of calls in a trending market.

In practice, if you receive a margin call and cannot meet it by the broker's deadline — often the morning of the next trading session — the broker has the right to liquidate the position without further notice. There is no negotiation. This is not a feature of bad brokers; it is a contractual term every futures account holder agrees to at opening, and it is why position sizing relative to available capital matters as much as any directional view.