Key Takeaways

Cross margin uses the account's broader available equity to support open positions, while isolated margin assigns a specific collateral amount to one position. The choice affects which funds can be drawn on when a trade moves adversely.

Under cross margin, a losing position can draw on broader available account equity until venue maintenance requirements are breached. This can keep the position open longer, but it means more of the account balance is exposed to that trade's mark-to-market losses.

Under isolated margin, the position is designed to draw only on the margin assigned to it; other account equity is generally not used automatically to support that position unless the trader adds margin or venue rules specify otherwise.

When two positions run in the same cross-margin account, a loss on one trade reduces the shared equity pool and lowers the effective collateral supporting the other. Under isolated margin, each position's collateral is designed to remain ring-fenced unless margin is added or venue rules specify otherwise.

Changing margin mode does not alter the funding rate, the notional size of the position, or the contract's settlement structure; it changes only the scope of collateral the venue can draw on if maintenance margin requirements are breached.

Why Margin Mode Matters

Two traders can hold the same BTC perpetual futures position at the same leverage and watch the same adverse price move produce different account outcomes. That is the central distinction in cross margin vs isolated margin: one position may draw only on the margin assigned to that trade, while the other may keep pulling from the broader account balance until venue maintenance requirements are breached.

The variable responsible is not position size, not leverage ratio, and not the asset being traded. It is margin mode: the setting that determines which portion of the account's capital is available to support a position when losses build.

Margin mode typically appears in perpetual trading interfaces alongside the leverage selector. The two settings look similar, and both affect how a position behaves under stress. They are, however, mechanically independent. Leverage sets the ratio of notional exposure to posted margin. Margin mode sets the scope of collateral that backs the position, either shared across the relevant margin account or ring-fenced to that position alone.

That distinction becomes material when a position is absorbing losses or when multiple positions are open at the same time. On venues that support both modes, the choice between cross and isolated margin affects account dynamics in ways that go beyond the trade itself.

What Is Cross Margin?

Cross margin is a collateral arrangement in which eligible available equity in the same margin account can serve as the buffer for cross-margin positions. A position running under cross margin is not backed only by a fixed slice of capital. It can draw on the broader eligible balance in that account.

When a position moves adversely, unrealized losses reduce total account equity. Because eligible cross-margin positions in the same margin account draw from the same pool, a drawdown on one position compresses the margin coverage available to the others. The position continues absorbing losses as long as the relevant account equity meets the venue's combined maintenance margin requirements.

The term "cross margining" also appears in traditional finance, where clearing and margin rules can treat related positions differently from standalone exposures. That clearing context is different from the account-level margin mode described here, but it sits in the broader market structure covered in the guide to perpetual futures vs traditional futures.

What Is Isolated Margin?

Isolated margin is a collateral arrangement in which a specific amount of collateral is assigned to a single position at open. That assigned amount is the primary buffer for the position. Equity held elsewhere in the account is generally not drawn automatically to support it.

When the position moves adversely, losses draw against the assigned margin. If the assigned margin falls to the venue's maintenance requirement for that position, liquidation of that specific position can begin without automatically drawing on the rest of the account balance and without directly affecting other open positions.

The trader selects the margin amount when opening the position, and that assignment defines the scope of capital directly exposed to the trade under normal operating conditions. If the trader wants to increase the buffer, they typically need to add margin to that specific position, subject to venue rules; idle equity elsewhere in the account does not apply automatically.

Cross Margin vs Isolated Margin — Side-by-Side

Four Key Mechanical Differences

What Capital Backs the Position

The two modes differ at the most fundamental level in which capital supports each open position.

Under cross margin, eligible equity in the same margin account forms a shared pool. Cross-margin positions in that account can draw on that pool. A position absorbing losses reduces it; a position generating gains adds to it. Idle balance in the relevant margin account can contribute to margin coverage for cross-margin positions.

Under isolated margin, each position is assigned a specific amount at open. Gains and losses are settled against that amount unless the trader adds margin or the venue's rules provide another path. Idle equity in the account does not automatically increase the isolated position's buffer. If the assigned margin is consumed, the position approaches liquidation even if capital sits elsewhere in the account.

Liquidation Boundary

The threshold at which a position faces liquidation is defined differently under each mode.

Under cross margin, a position approaches liquidation when the relevant account equity falls to the venue's combined maintenance margin requirement for the cross-margin positions it supports. The relevant threshold is account-level equity, not only the margin initially posted for that specific trade. A single adverse move on one position can reduce overall account equity enough to threaten the margin coverage for other trades in the account, including smaller, hedged, or currently profitable positions.

Under isolated margin, the liquidation boundary is position-specific. A position faces liquidation when its assigned margin falls to the maintenance requirement for that position alone. The calculation for that position is independent of any other position's performance.

Whether isolated margin reaches its liquidation threshold sooner or later than a cross-margin position depends on account composition. An account with substantial idle equity running cross margin has a larger total buffer than any single isolated assignment; the same account under isolated margin preserves that idle equity as unassigned capital that is not used automatically as the position's buffer.

Multi-Position Account Dynamics

Running two or more positions simultaneously is where the mechanical difference between the two modes has its most visible effect on the account.

Under cross margin, a loss on one position directly reduces the equity available to support other cross-margin positions in the same margin account. Two simultaneously losing positions compound against the same pool. The interdependence is a structural property of shared-equity accounts, not a venue-specific quirk. Adding more open positions to a cross-margin account increases both the potential buffer from idle equity and the potential for simultaneous losses to draw down that buffer from multiple directions at once.

Under isolated margin, each position's collateral is generally contained to its own assignment. A loss on Position A does not automatically draw from Position B's assigned margin. Position B faces its own liquidation calculation based on its assigned collateral, the price of the asset it tracks, and any venue-specific rules that apply.

Adding More Margin

The two modes also differ in how extra collateral reaches a stressed position.

Under cross margin, adding funds to the relevant margin account can increase the shared equity pool that supports open positions. The added capital usually does not need to be assigned to one specific trade first.

Under isolated margin, increasing the buffer usually requires adding margin to the specific position. That gives the trader more position-level control, but it also means idle equity elsewhere in the account does not automatically help the position absorb losses.

Worked Example — Same BTC Position, Two Margin Modes

The example below uses illustrative numbers to isolate the margin mode effect. Funding accrued, liquidation fees, maintenance margin buffers, and venue-specific rules are excluded. Actual liquidation thresholds vary by venue.

Account: $2,000 USDC. Position A: BTC perpetual long, 10x leverage, $200 initial margin, $2,000 notional exposure.

Under isolated margin: $200 is assigned to Position A at open. BTC then moves 8% in the unfavorable direction. Mark-to-market loss: 8% × $2,000 notional = $160. The assigned margin falls from $200 to $40, approaching the maintenance margin level at which the venue could begin liquidation proceedings. The remaining $1,800 in the account is not drawn automatically to support Position A unless the trader adds margin or venue rules specify otherwise.

Under cross margin: $200 is the initial margin posted, but the full $2,000 account is in the relevant margin account for this simplified example. BTC moves the same 8% in the unfavorable direction. The $160 loss reduces total account equity from $2,000 to $1,840. Position A remains open. The $1,800 that was not available as an automatic buffer under isolated margin is now part of the shared equity buffer for Position A. The same adverse move that brought the isolated position close to its maintenance threshold has reduced cross-margin account equity by 8%.

Two-position extension. Add Position B: ETH perpetual short, 5x leverage, $200 initial margin, $1,000 notional exposure. Both positions share the $2,000 account under cross margin.

BTC then moves 8% in the unfavorable direction for Position A: loss = 8% × $2,000 = $160. ETH simultaneously moves 8% in the unfavorable direction for Position B (price moves adversely for the short): loss = 8% × $1,000 = $80. Combined unrealized loss: $240. Account equity falls to approximately $1,760.

The venue now evaluates both positions against the combined maintenance margin requirement. This example is not meant to show cross margin near liquidation. It shows the shared-equity effect: losses from both positions reduce the same account-level collateral pool.

Under isolated margin, the same price moves produce a different collateral outcome. Position A's $160 loss draws against its $200 assigned collateral and may push that position toward its individual liquidation threshold. Position B's $80 loss draws against its own $200 assignment. The two assignments remain separate in this simplified example because the positions have separate isolated-margin assignments and no manual margin transfer occurs.

*Simplified example; actual liquidation prices vary by venue, maintenance margin rate, funding accrued, and liquidation fees.*