Cross-collateral allows eligible assets to support positions whose settlement currency differs from the collateral asset. For example, a platform may accept BTC holdings as support for a contract whose profit and loss settle in a stablecoin. Acceptance depends on the specific account and product rules.
Valuation is not necessarily conversion
The risk system values collateral in a common unit and may apply discounts, limits or reserves. If a hypothetical asset worth 10,000 USD receives an 80% collateral recognition ratio, it contributes 8,000 USD before other account adjustments. This is neither a promised borrowing amount nor a leverage limit.
Using an asset as collateral does not necessarily sell it into the settlement currency. Losses or fees in another currency can create a negative balance that must be addressed under the platform's borrowing, conversion or rebalancing rules. Associated charges vary.
Two sources of pressure
A falling collateral price can reduce support while a trading position also loses value. Concentrated or correlated holdings can therefore weaken the account from both sides. Eligibility and valuation ratios may change as well.
Cross-collateral concerns which assets are accepted. Cross margin concerns how margin is shared across positions, while portfolio margin concerns how combined risk determines requirements. These features can coexist but are not interchangeable. The account's withdrawal restrictions and liquidation rules determine what happens when available support becomes insufficient.