Initial margin is the upfront deposit you post before a derivatives position opens; variation margin is the daily cash payment that settles the gains and losses on that position as prices move. Both sit inside the same collateral system, but they answer different questions. The difference between initial margin and variation margin comes down to timing and purpose: initial margin covers what the market might do to your position between a default and its liquidation, while variation margin settles what the market did do since yesterday’s close.
What Initial Margin Is
Initial margin is a security deposit held by the clearing house or a third-party custodian. Its size is set to cover the worst-case price swing that could realistically occur over the time it would take to liquidate the position if you defaulted.
That liquidation window drives the number. 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 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 dollar amount comes out of a statistical risk model. Exchanges have historically used CME’s Standard Portfolio Analysis of Risk (SPAN), and CME is gradually transitioning to its successor, SPAN 2.3CME Group. SPAN 2 Methodology and Functionality For non-cleared over-the-counter derivatives, most firms use the ISDA Standard Initial Margin Model (SIMM), a Value-at-Risk approach calibrated to stress periods.4ISDA. ISDA SIMM The required amount depends on volatility, position size, and how well positions in the portfolio offset each other.
The numbers can be substantial. 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 level.5CME Group. E-mini S&P 500 Futures Margins Once posted, initial margin generally stays put unless you significantly change position size or the clearing house raises requirements because of elevated volatility. Both sides of a trade post it, so the clearing house holds collateral from each counterparty simultaneously.
What Variation Margin Is
Variation margin is the daily settlement of profit and loss. Every day, the clearing house re-prices every open contract using the settlement price. If your position lost value, you pay that amount. If it gained value, you receive it. The process is called mark-to-market.
The calculation is simple arithmetic: change in settlement price, multiplied by contract size, multiplied by the number of contracts held. No risk model needed.
This daily sweep exists to keep unrealized losses from quietly building until a counterparty can’t pay. By zeroing out P&L each day, variation margin ensures that market risk exposure never compounds overnight.6ISDA. Accounting Impact of CCPs Rulebook Changes to Financial Institutions and Corporates For centrally cleared futures, variation margin flows as netted cash between each clearing member and the central counterparty, with the CCP collecting from losers and paying winners with finality.7Federal Reserve Bank of Chicago. Cleared Margin Setting at Selected CCPs Unlike initial margin, variation margin only moves one direction on any given day: from the losing party to the winning party. Tomorrow the direction can reverse.
The Core Difference at a Glance
The two margin types address different risks through different mechanisms, but together they form one protection system.
- Initial margin is a credit risk tool; variation margin is a market risk tool.
- 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 between counterparties every day.
- Initial margin comes from both sides at once; variation margin flows one direction each day, from loser to winner.
- Variation margin is generally posted in cash; initial margin can be posted in a wider range of assets, each subject to a haircut.
The interplay becomes clearest during a default. 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. If a member’s own initial margin and default fund contributions are still not enough, the clearing house draws on its own capital and then on pooled contributions from surviving members through a structured default waterfall.8CCP Global. CCP Lines of Defence
Margin Calls and the Maintenance Threshold
Variation margin is what actually triggers most margin calls, and the trigger point is called the maintenance margin. It sits below the initial margin level to give room for normal price fluctuations before the alarm goes off.
Thresholds vary 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 their own house requirements at 30% or 40%.9FINRA. FINRA Rule 4210 – Margin Requirements For futures, the exchange sets both initial and maintenance levels, with maintenance typically running somewhat below the initial requirement.
When adverse variation margin adjustments push your balance below the maintenance level, the clearing member issues a call. You have to deposit enough to bring the account back up to the full initial margin level, not just past the maintenance floor. Firms can liquidate your positions if you don’t meet the call, and they’re not required to give you a specific grace period before doing so.10FINRA. Know What Triggers a Margin Call Some brokers informally allow two to three business days; others sell you out the same day. The firm can also sell more than necessary to cover the shortfall.
Clearing houses don’t always wait until the end of the day either. In fast markets, intraday margin calls can be issued whenever losses have grown large enough to warrant immediate action, and members have very short windows to meet them. The Options Clearing Corporation, for instance, gives members 60 minutes to meet an intraday call.11OCC. Intraday Margin Call Process Participants who hold cash only up to their end-of-day obligation can find themselves short during a volatile session.
What You Can Post as Collateral
The collateral rules differ between the two margin types. Variation margin for centrally cleared products is generally posted in cash, because the receiving party needs immediate liquidity. Initial margin allows a wider menu of assets, but each one is subject to a haircut that reduces its credited value below market price.
For non-cleared derivatives, global standards set by BCBS and IOSCO provide a list of eligible initial margin collateral along with standardized haircuts:12BIS. Margin Requirements for Non-Centrally Cleared Derivatives
- Cash: 0% haircut, but only when denominated in the same currency as the derivatives obligation.
- Government and central bank securities: 0.5% to 4% haircut depending on maturity.
- High-quality corporate and covered bonds: 1% to 8% haircut depending on maturity.
- Equities in major stock indices: 15% haircut.
- Gold: 15% haircut.
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 means losing 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. If your counterparty goes bankrupt, your posted collateral isn’t trapped in their estate.
Where the Rules Come From
The margin requirements most traders encounter are not optional, and they aren’t set by a single authority.
For equity securities, the Federal Reserve’s Regulation T sets initial margin at 50% of purchase price,13SEC. Understanding Margin Accounts with FINRA’s 25% maintenance minimum on top.9FINRA. FINRA Rule 4210 – Margin Requirements Security futures carry a separate 15% margin requirement under joint SEC and CFTC rules.14eCFR. 17 CFR 41.45 – Required Margin For commodity futures, the exchanges set margin levels under CFTC oversight, which is why numbers like E-mini S&P 500 requirements can change week to week.
The Dodd-Frank Act required U.S. banking regulators to adopt margin and capital requirements for swap entities, extending mandatory initial and variation margin to non-cleared swaps that had previously operated without standardized collateral rules.15Board of Governors of the Federal Reserve System. Margin and Capital Requirements for Covered Swap Entities The European Market Infrastructure Regulation imposed parallel requirements in Europe. Initial margin for these transactions must be calculated using either a regulatory-approved model like ISDA SIMM or a more conservative standardized grid schedule published by regulators.16ISDA. ISDA SIMM – The Trusted Standard for Initial Margin Calculations Dodd-Frank also required certain standardized swaps, primarily interest rate swaps and credit default swaps in major currencies, to be centrally cleared.17OCC. Commodity Futures Trading Commission Swap Clearing Rules
The result: whether you’re trading a stock on margin, a futures contract on an exchange, or a bilateral swap between two banks, both types of margin apply, and the mechanics that separate them are built into law.