# Mutualized Perps (mPerps)

A mutualized perpetual, or mPerp, is a Meridian market that tracks a real-world asset (RWA) reference, such as a commodity or equity index. mPerps use isolated margin, scheduled mark-price gaps, and position fees for limited reference-market sessions.

## Reference-Market Schedules

A reference-market schedule defines when the underlying market is open or closed. It includes regular trading sessions and special closures such as market holidays.

Meridian publishes each known closure as a mark-price gap through `GET /v1/product/mark-price-gap`. A gap has a `startTime` and an `endTime`. Times are Unix milliseconds.

Schedules can change. Integrations should use the API rather than a fixed weekly timetable.

## What Happens During a Mark-Price Gap

At the start of a scheduled gap, Meridian freezes the last accepted oracle mark.

During an active gap:

* The mark does not follow order-book trades.
* Position fees can apply to open positions.
* Trading can continue while the product remains active.

At reopen, the next accepted mark can gap from the frozen value. A frozen mark can delay a stop trigger until the gap ends.

## Isolated Margin

Each mPerp uses an isolated quote-token margin pool backed by the exchange USD token.

Risk is contained within that quote-token pool. Collateral converts 1:1 between the exchange USD token and the applicable isolated quote token; the isolated token cannot be deposited or withdrawn directly.

The product API returns `marginMode: "ISOLATED"` for these markets. See [Margining](/trading/perpetual-futures/margining) and [Supported Tokens](/developer-guides/trading-api/supported-tokens).

## Position Fees

A position fee can apply to long and short positions during a scheduled mark-price gap. It is separate from funding.

The API publishes the charge schedule, projected rate, and applied charges. See [Position Fees](/trading/perpetual-futures/position-fees).

mPerps add session-gap, schedule, liquidity, tracking, and oracle risk. The next mark-price gap and projected position fee are available through the Trading API.