Bybit's Unified Account: Isolated, Cross and Portfolio Margin Compared

One account, three ways to decide what margin means

Bybit’s Unified Trading Account centralises spot, futures and options into one account and supports more than seventy assets as collateral. The part that matters for risk is not the consolidation; it is the margin mode, because that is the setting that decides which assets count, which positions can subsidise which, and what number has to reach a threshold before the venue starts closing things.

Bybit documents three modes: Isolated Margin (IM), Cross Margin (CM) and Portfolio Margin (PM). Cross is the default. The API names them ISOLATED_MARGIN, REGULAR_MARGIN and PORTFOLIO_MARGIN, which is a useful reminder that “regular” and “cross” are the same thing in Bybit’s vocabulary.

The first constraint is scope. The selected mode applies to the entire account, and Bybit states plainly that you cannot choose different margin modes for individual trading pairs. This is not a per-symbol setting that happens to live in the account page; it is an account-wide risk regime.

The comparison that decides the choice

Bybit publishes a side-by-side table. Reduced to the rows that change behaviour, it looks like this:

Two rows deserve more than a table cell.

Asset mode is the real dividing line. Under Single Asset Mode, USDT can only be used to trade USDT contracts and USDC can only be used for USDC contracts. Under Multiple-Assets Mode, every collateralised asset is converted into USD value and that value can support Spot Margin and derivatives trading — Bybit’s own example is holding BTC and using its USD value as collateral for a USDT perpetual. The same BTC balance is therefore worth different amounts of margin in different modes, before any position is opened.

The liquidation trigger changes what the liquidation price means. In Isolated Margin, the displayed liquidation price is the actual trigger: the mark price reaches it and that position is liquidated. In Cross and Portfolio Margin, the displayed liquidation price is an estimate, because the real trigger is the account Maintenance Margin Rate reaching 100%. A position can be deep in loss without being liquidated if the rest of the account is carrying it, and a position can be profitable while the account is liquidated because another position consumed the buffer.

Isolated Margin: a wall around each position

Isolated Margin is the mode to choose when the question is “what is the most this position can lose?” It calculates margin on the individual position, runs in Single Asset Mode, supports spot and derivatives but not Spot Margin or options, and allows different leverage for long and short positions.

The cost of that wall is visible in four rows of Bybit’s table: no offsetting of derivatives P&L, no use of unrealised profits to open new positions, and no borrowings. A profitable short cannot rescue a losing long, and a paper gain cannot be spent. What Isolated Margin does offer is automatic margin replenishment, which Cross and Portfolio Margin do not list.

For a trader running one directional position with a defined stop, that is a coherent bargain. For a trader running a hedged pair, it is the wrong tool, because the hedge’s profit sits on the other side of a wall.

Cross Margin: one pool, one ratio

Cross Margin is the default and the mode most accounts will use without choosing it. It adds Spot Margin and options, moves to Multiple-Assets Mode, and calculates initial and maintenance margin at the account level.

Three consequences follow from that design:

• Collateral is converted, not segregated. All collateralised assets are valued in USD and can support Spot Margin and derivatives. The amount of margin a balance provides depends on Bybit’s collateral value ratio for that asset, not on its face value.
• P&L offsets. A profit on one derivatives position can cover a loss on another, and unrealised profits can be used to open new positions. This is the capital efficiency Bybit is selling, and it is also the mechanism by which one bad position can endanger the account.
• Liquidation is a ratio, not a price. The account MMR reaching 100% is the trigger. The displayed liquidation price for a position is an estimate for that reason.

Cross Margin also enables borrowings and disables automatic margin replenishment. A trader who expects the venue to top up a margin call should read that row twice: the mode that pools collateral is also the mode that does not refill it automatically.

Portfolio Margin: risk priced across the book

Portfolio Margin is aimed at professional derivatives traders. It still supports spot, Spot Margin, perpetuals, futures and options, and it still liquidates at account MMR of 100%, but it calculates margin from the risk of the whole portfolio rather than from the sum of position-level requirements. A well-balanced book with offsetting exposures can therefore require less margin than the same positions would under Cross.

The restriction is the price of that calculation: Portfolio Margin is one-way mode only. Hedge-mode orders and positions are not permitted. Bybit’s switching rules also require no orders or positions in hedge mode before the move, and an Initial Margin Rate at or below 100% after it.

This is the mode where reading the venue’s own margin methodology matters most. A portfolio risk model that recognises hedges will also recognise the cases where a hedge is imperfect, and the number it produces is not a simple percentage of notional.

Switching is a risk event, not a settings change

Bybit documents the conditions for each direction, and they are operational rather than cosmetic.

Into Isolated Margin: no options orders or positions, no Spot Margin Trading orders, no existing borrowings, Spot Margin Trading disabled, sufficient assets to cover the increased margin, the mark price of each existing position not worse than the liquidation price it would have after the switch, and enough assets to allocate to each position without triggering liquidation. After the switch, Spot Margin, auto margin replenishment and collateral switching are disabled by default.

Into Cross Margin: the Initial Margin Rate must be at or below 100% after the switch. If inverse contracts are held, their settlement assets are enabled as collateral. If long and short positions used different leverage under Isolated Margin, the system aligns both to the lower leverage; if they sit in different risk limit tiers, leverage follows the tier with the higher requirement.

Into Portfolio Margin: the Initial Margin Rate must be at or below 100% after the switch, and no orders or positions may be in hedge mode. Spot Margin is enabled by default, and inverse settlement assets are enabled as collateral if inverse contracts are held.

The pattern is consistent: moving toward more isolation requires unwinding the products that depend on a pooled account, and moving toward more pooling requires the account to be able to absorb the new margin requirement without breaching it. A switch attempted at the edge of a margin call is a switch that will be rejected or, worse, accepted and immediately liquidated.

What to check before choosing

The mode is account-wide, so the decision should be made against the whole book rather than against the next trade.

1. List the products. If the strategy uses options or Spot Margin, Isolated Margin is out. If it uses hedge mode, Portfolio Margin is out.
2. List the collateral. If the account holds BTC, ETH or another non-settlement asset and expects it to support USDT contracts, Single Asset Mode will not do that.
3. Decide what a liquidation should mean. A per-position trigger is predictable and wasteful; an account trigger is efficient and contagious. Neither is safer in the abstract.
4. Read the liquidation price correctly. Under Cross and Portfolio Margin it is an estimate. The number to watch is the account Maintenance Margin Rate.
5. Plan the switch as a trade. Reduce positions, repay borrowings, close options and hedge-mode legs, then change the mode. The switching checklist is a description of the state the account must be in, not a confirmation dialog.

The mechanics of the account-level ratio are the same arithmetic that turns a margin call into a forced sale, covered in margin calls and the arithmetic behind a forced sale. Why the liquidation price and the bankruptcy price are different numbers is covered in liquidation price versus bankruptcy price. For the order-level exits that sit on top of either mode, see Bybit TP/SL: full versus partial, trigger source and reduce-only, and for the funding cost that accrues while a position is open, Bybit funding fees with a worked example.

Risk note. The margin modes, supported products, liquidation triggers, switching conditions and API values in this article were read from Bybit’s help centre and V5 API documentation on 2026-11-02. Margin rules change; the account-level consequences of pooling collateral do not. Nothing here is investment advice.