Initial margin is the upfront deposit you post before opening a derivatives position; variation margin is the daily cash payment that settles the gains and losses on that position as prices move. The short way to hold the difference between initial margin and variation margin in your head: initial margin covers what the market might do to your position, and variation margin covers what the market did do. They sit side by side in every cleared trade, but they answer different questions and follow different rules.
What Initial Margin Is
Initial margin is the capital you deposit before a trade goes through. The clearing house holds it as a security deposit so that if you default, there is enough on hand to close out your position without anyone else absorbing the loss. It is sized to cover the worst-case price swing that could realistically happen over the time it would take to liquidate you.
That liquidation window depends on the product. For exchange-traded futures, clearing houses like CME typically use a one- to two-day margin period of risk.1CME Group. Key Facts on Margining of CME FX Futures and Options For non-centrally cleared derivatives between large institutions, global regulators require a much wider buffer: a 99th-percentile loss estimate over a 10-day horizon.2IOSCO. Margin Requirements for Non-Centrally Cleared Derivatives Illiquid or complex positions take longer to unwind, so the cushion is bigger.
The size of the deposit comes out of statistical risk models. Exchanges have historically used CME’s Standard Portfolio Analysis of Risk (SPAN) methodology, though CME is gradually moving to a successor framework, SPAN 2.3CME Group. SPAN 2 Methodology and Functionality For non-cleared OTC derivatives, most firms use the ISDA Standard Initial Margin Model (SIMM), a Value-at-Risk approach calibrated to stress periods.4ISDA. ISDA SIMM Either way, the required amount reflects volatility, position size, and how well positions in the portfolio offset each other.
The dollar figures are meaningful. Maintenance margin for a single E-mini S&P 500 futures contract at CME runs roughly $24,000 to $25,000 as of mid-2026, with initial margin set slightly above that.5CME Group. E-mini S&P 500 Futures Margins That is a small fraction of notional value, but it is real capital locked up for the life of the trade.
Once posted, initial margin generally stays put. It moves only if you change position size significantly or the clearing house raises requirements because volatility spikes. It sits in segregated, liquid assets, available immediately if needed.
What Variation Margin Is
Variation margin is the daily cash settlement that reflects how much your position gained or lost since the previous trading day. Every day, the clearing house re-prices every open contract using the settlement price. If your position lost value, you pay. If it gained value, you receive. This is called mark-to-market, and it happens whether you want it to or not.
The daily sweep prevents a specific danger: unrealized losses quietly building until a counterparty can no longer pay. Zeroing out profit and loss each day keeps market risk exposure from compounding overnight.6ISDA. Accounting Impact of CCPs Rulebook Changes to Financial Institutions and Corporates Neither side wakes up owing a week of accumulated losses.
The calculation is arithmetic. Change in settlement price, multiplied by contract size, multiplied by the number of contracts. No risk model required.
For centrally cleared futures, variation margin flows as netted cash between each clearing member and the central counterparty. The CCP collects from members with losing positions and pays members with winning positions, with finality.7Federal Reserve Bank of Chicago. Cleared Margin Setting at Selected CCPs The cash-only requirement is deliberate. When you owe variation margin, the other side needs liquidity, not a bond they would have to sell first.
How the Two Differ in Practice
The two margin types cover different risks through different mechanisms, and together they form one protection system. Initial margin is a credit risk tool. It guards against a counterparty defaulting and being unreachable for further payments. Variation margin is a market risk tool. It settles the price movement that has already occurred.
A few distinctions worth keeping straight:
- Initial margin is based on what the market might do; variation margin is based on what the market did.
- Initial margin sits with a custodian and stays relatively static; variation margin moves back and forth every day.
- Both sides of a trade post initial margin, so the clearing house holds collateral from each counterparty at the same time. Variation margin flows in only one direction on any given day, from the losing party to the winning party. Tomorrow the direction can reverse.
- Variation margin is generally cash. Initial margin allows a wider range of collateral, at a cost (see below).
The interplay becomes clearest during a default. If a clearing member fails, the clearing house first uses the daily variation margin process to settle any outstanding gains and losses up to that point. Then it turns to the initial margin to cover the cost of liquidating or transferring the defaulter’s portfolio. Initial margin exists precisely for the gap between the last variation margin payment and the moment the position is fully closed out.
Margin Calls: Where the Two Meet
A margin call is a demand for additional funds when equity in your account drops below a required threshold. That threshold is the maintenance margin, and it sits below the initial margin level to give some room for normal price moves before the alarm goes off. Variation margin losses are what push you toward the threshold; a margin call is what happens when you cross it.
The maintenance level varies by market. For equity securities held on margin, FINRA requires a minimum of 25% of the current market value of long positions, though individual firms routinely set house requirements at 30% or 40%.8FINRA. FINRA Rule 4210 – Margin Requirements For futures, the exchange sets both initial and maintenance levels, with maintenance typically somewhat below the initial requirement.
When your balance drops below maintenance, the clearing member issues a call. You must deposit enough to bring the account back up to the full initial margin level, not just past the maintenance floor. The call restores the original buffer, not the bare minimum.
Firms can liquidate your positions if you don’t meet the call, and they’re not required to give you a specific grace period.9FINRA. Know What Triggers a Margin Call Some brokers informally allow two to three business days; others sell the same day. The firm can also sell more than necessary to cover the shortfall. This is where people lose more than they expected, because the forced liquidation almost always lands at the worst price.
What You Can Post as Collateral
The collateral rules diverge sharply between the two. Variation margin for centrally cleared products is generally cash, because the receiving party needs immediate liquidity. Initial margin allows a wider menu of assets, each subject to a haircut that reduces its credited value below market price.
For non-cleared derivatives, global standards set by BCBS and IOSCO define eligible initial margin collateral along with standardized haircuts:10BIS. Margin Requirements for Non-Centrally Cleared Derivatives
- Cash in the same currency as the derivatives obligation: 0% haircut.
- Government and central bank securities: 0.5% to 4%, depending on maturity.
- High-quality corporate and covered bonds: 1% to 8%, depending on maturity.
- Equities in major stock indices: 15%.
- Gold: 15%.
An additional 8% haircut applies whenever the collateral currency differs from the currency of the derivatives obligation. Posting euro-denominated bonds against a dollar-denominated swap costs an extra 8% of credited value on top of the standard haircut.
For non-cleared derivatives, initial margin must be held with an independent third-party custodian rather than with the counterparty. That segregation matters: if your counterparty goes bankrupt, your posted collateral isn’t trapped in their estate. The custodian holds the assets under an account control agreement that spells out when and how the collateral can be released. Variation margin, being cash that changes hands daily, doesn’t sit still long enough to need that structure.