Initial vs Maintenance Margin: Why Leverage Capacity Is Not a Risk Budget

Initial vs Maintenance Margin: Why Leverage Capacity Is Not a Risk Budget

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Evergreen trading tutorial: The examples below are hypothetical. Margin rules vary by broker, exchange, product and jurisdiction. This is educational information, not personalised advice or a recommendation to use leverage.

Margin allows a trader to control a position whose notional value is larger than the cash posted as collateral. That efficiency creates a dangerous misunderstanding: the maximum position a platform permits is not the amount a trader can prudently risk.

Initial margin determines whether a position can be opened. Maintenance margin determines how much equity must remain to keep it open. If account equity falls below the required level, the broker or exchange may request more funds, reduce the position or liquidate it automatically—sometimes before a trader can act.

Learning objective

By the end of this guide, you should be able to:

• distinguish notional exposure, initial margin and maintenance margin;
• calculate how a market move changes account equity;
• understand why liquidation can occur before an intended stop executes;
• separate platform leverage capacity from a personal risk budget; and
• size a hypothetical leveraged position from its stop distance.

The four quantities to separate

1. Notional exposure

Notional exposure is the market value controlled by the position. If a futures, CFD or leveraged crypto position represents £20,000 of the underlying asset, £20,000 is the notional exposure even if only £2,000 was posted.

Profit and loss normally respond to the notional position, not just the collateral. A 1% move against £20,000 of linear exposure creates about a £200 loss before fees, funding and contract-specific adjustments.

2. Initial margin

Initial margin is the collateral required to open the position. If the initial-margin rate is 10%, a £20,000 position requires £2,000:

£20,000 × 10% = £2,000 initial margin

This is a funding requirement. It does not mean the maximum possible loss is £2,000.

3. Maintenance margin

Maintenance margin is the minimum equity required to keep the position open. It is often lower than initial margin. If the maintenance rate is 7%, the threshold for a £20,000 notional position is £1,400 before any tiering or product-specific adjustment:

£20,000 × 7% = £1,400 maintenance requirement

The notional value and maintenance requirement can change as price moves. Many venues also increase margin rates for larger positions.

4. Free equity or margin buffer

Free equity is the amount remaining after the required margin and unrealised losses are considered. A thin buffer makes the account vulnerable to ordinary volatility, fees and gaps.

Different platforms use terms such as available margin, free margin, margin balance or collateral value. Read the product documentation rather than assuming the labels are identical.

Margin call and liquidation are not the same promise

A traditional margin call is a request to add funds or reduce exposure. Fast electronic markets may not provide a useful grace period. Some crypto and derivatives venues liquidate automatically once their risk engine reaches a threshold.

The trigger may use:

• a mark price rather than the last traded price;
• unrealised profit and loss across several positions;
• collateral haircuts for volatile assets;
• maintenance tiers based on notional size;
• fees, funding payments or accrued interest; and
• portfolio offsets that can change during stress.

Liquidation price shown by a platform is therefore an estimate under stated assumptions, not a guaranteed exit price. Slippage, partial liquidation and market gaps can produce a worse result.

Worked example: how the buffer disappears

Assume a hypothetical linear position with:

• notional exposure: £20,000;
• initial-margin rate: 10%;
• maintenance-margin rate: 7%;
• cash deposited to the account: £2,500; and
• no other positions.

The initial requirement is £2,000, leaving a £500 buffer at entry. The maintenance requirement is initially £1,400.

If the market falls 4% against the position:

£20,000 × 4% = £800 unrealised loss

Ignoring fees and changing notional for simplicity, account equity falls from £2,500 to £1,700. That remains £300 above the £1,400 maintenance threshold.

If price falls another 1.5% from the original entry reference:

£20,000 × 1.5% = £300 additional loss

Equity reaches about £1,400. Fees or a small further move can put the account below maintenance. The platform may then liquidate or demand more collateral.

This simplified example shows why “10% initial margin” does not mean price can safely move 10% against the position. The trader deposited only £500 more than the opening requirement, and a 5.5% adverse move consumed that entire buffer.

Real contracts may use non-linear payoffs, changing maintenance tiers, cross-collateral and different liquidation formulas. Always use the venue's calculation for the specific product.

Position sizing from planned risk, not maximum leverage

Suppose a separate hypothetical trading account has £10,000 of equity. The setup has:

• planned entry: £50;
• invalidation stop: £49;
• stop distance: 2% of the entry price; and
• example cash-risk budget: 0.5% of account equity, or £50.

For a linear position, theoretical notional exposure is:

£50 planned risk ÷ 2% stop distance = £2,500 notional

At a 10% initial-margin rate, the broker might require only £250 to open that £2,500 exposure. The platform may allow a much larger position because £10,000 of equity is available, but the risk plan—not the platform maximum—caps the example at £2,500 notional.

If the intended stop moves from 2% to 4%, the notional should fall to £1,250 to keep planned price risk near £50:

£50 ÷ 4% = £1,250

The position-sizing guide explains the same principle for unit-based trades. Leverage changes how much collateral is required; it does not remove the underlying price risk.

Why a stop does not eliminate liquidation risk

A stop order may fail to protect the intended amount when:

• price gaps beyond the trigger;
• the order book is thin;
• the venue pauses or rejects orders;
• liquidation uses a different mark price;
• fees reduce equity before the stop; or
• several correlated positions lose together.

The planned stop should normally sit well before the estimated liquidation level. A tiny gap between the two gives the broker's risk engine control over the exit. Our overnight gap-risk guide explains why a closed market can bypass a stop.

Cross margin versus isolated margin

Cross margin generally allows eligible account equity to support multiple positions. It can delay liquidation of one trade, but a losing position may consume collateral intended for the rest of the account.

Isolated margin generally limits assigned collateral to one position. It can contain damage, but the position may liquidate sooner because it cannot draw on the wider account.

Neither structure is automatically safer. Safety depends on size, correlation, liquidation rules, collateral quality and whether the trader understands how the platform reallocates equity.

Common mistakes

1. Treating margin posted as maximum loss. Profit and loss respond to notional exposure.
2. Using all available buying power. Platform capacity is not a risk budget.
3. Confusing initial and maintenance margin. One opens the position; the other keeps it open.
4. Assuming a margin call provides time. Automated liquidation can occur immediately.
5. Placing the stop near liquidation. Mark price, fees or slippage may trigger liquidation first.
6. Ignoring correlation. Several positions can behave like one concentrated exposure.
7. Using volatile collateral at full face value. The collateral can fall while the trade loses.
8. Forgetting funding and fees. Carry costs reduce equity and the liquidation buffer.
9. Trusting one displayed liquidation price. Rules and maintenance tiers can change.

Practical checklist

• Product notional and payoff formula are understood.
• Initial and maintenance rates are checked for the exact size tier.
• Mark-price and liquidation methodology are read from the venue documentation.
• Cross or isolated margin treatment is known.
• Position size comes from planned loss and stop distance.
• The stop is meaningfully before the estimated liquidation level.
• Fees, funding, interest, spread, slippage and gaps are included.
• Correlated positions are combined when measuring account risk.
• Collateral haircuts and currency risk are considered.
• A stress test covers a move larger than the intended stop.

The Money Man View

Margin should be treated as a financing mechanism, not a sizing instruction. The safe analytical sequence is to define the trade thesis, place invalidation, calculate notional exposure from the acceptable loss, and only then check whether the margin requirement fits the account. Reversing that order—starting with maximum leverage and searching for a stop afterwards—lets the platform's liquidation rules define the risk.

Educational risk disclosure: Leveraged trading can produce rapid losses and may lose more than the collateral posted, depending on the product and jurisdiction. The rates, percentages and prices above are simplified hypothetical examples, not recommendations. This article was prepared with AI-assisted research and writing under The Money Man editorial process.