> ## Documentation Index
> Fetch the complete documentation index at: https://docs.arcus.xyz/llms.txt
> Use this file to discover all available pages before exploring further.
# Margin & leverage
> How initial and maintenance margin work on Arcus perps, leverage limits, and the higher initial-margin regime when an underlying market is closed
Perps are traded on **margin**: you post collateral and control a larger position with leverage. Two thresholds govern every position — **initial margin** (what you need to open or increase a position) and **maintenance margin** (the minimum you must keep to avoid [liquidation](/concepts/perpetuals/liquidations)).
This page is conceptual. Live per-market margin and leverage parameters come from [`GET /v1/markets`](/api-reference/public/get-markets); your account's current margin and equity come from [`GET /v1/account`](/api-reference/public/get-account).
## Collateral
Collateral is held as **USDG**, the protocol's settlement stablecoin, in your Arcus account. Your account equity is your collateral balance plus the unrealized profit and loss of your open positions. See [Onboarding & deposits](/concepts/onboarding) for how funds arrive as USDG.
## Initial vs. maintenance margin
| Term | What it controls |
| - | - |
| **Initial margin** | The collateral required to open a new position or add to an existing one. Higher initial margin = lower maximum leverage. |
| **Maintenance margin** | The minimum collateral a position must retain. If equity falls below this level, the position becomes eligible for [liquidation](/concepts/perpetuals/liquidations). |
Each market sets its own initial and maintenance margin requirements based on its risk profile, expressed as a fraction of position notional.
## Cross and isolated margin
Arcus supports both **cross margin** (positions share the account's collateral, so the whole balance backs every position) and **isolated margin** (collateral is allocated to a single position, capping its risk to that allocation). Every position is cross margin by default; isolated margin is live and can be enabled per market.
See [Cross & isolated margin](/concepts/perpetuals/margin-modes) for how each mode measures risk, how to switch modes, and how to move collateral onto and off an isolated position.
## Leverage
Leverage is the inverse of the initial margin requirement. Arcus supports up to **50x** leverage; the maximum is set per market and published with each market's parameters. Higher-volatility or less-liquid markets carry lower maximum leverage.
## Off-hours margin
For perps whose underlying has set trading hours (equities, commodity and index ETFs), Arcus **raises the initial margin requirement while the underlying market is closed**. This makes it more capital-intensive to open or grow positions during thin overnight and weekend liquidity, reducing the risk of disorderly moves and liquidation cascades.
Maintenance margin is **not** raised off-hours — existing, adequately-margined positions are not pushed toward liquidation simply because the market closed. Crypto perps have no off-hours regime; their margin requirements are constant.
### Crossing the session boundary
The uplift is not a one-off charge applied at the close — it is a function of the market's **current** session state, so it switches on at the RTH → off-hours boundary and switches back off when the session reopens:
| Transition | Initial margin | Maintenance margin |
| - | - | - |
| **RTH → off-hours** (close, weekend, holiday) | Rises to `offHoursInitialMarginFraction` | Unchanged |
| **Off-hours → RTH** (reopen) | Returns to `initialMarginFraction` | Unchanged |
Nothing is snapshotted or carried over: the requirement reverts to exactly the in-session value at the reopen, and the effective maximum leverage recovers with it. Read the current state from [`GET /v1/markets`](/api-reference/public/get-markets) — `isOutsideRth` tells you which of the two fractions is live, and `regularTradingHours` gives the session window (it is `null` for 24/7 crypto markets, which never transition).
Across every RWA market today, `offHoursInitialMarginFraction` is **1.5× the in-session `initialMarginFraction`** — a flat 50% increase in the initial-margin requirement while the underlying is closed. Effective maximum leverage drops in step: a market you can open at 10x in-session tops out near 6.7x off-hours, and a 5x market near 3.3x. This is the current configuration rather than a fixed protocol rule — the fractions are per-market, so read both fields from `GET /v1/markets` instead of hard-coding the ratio.
Two consequences worth designing for:
* **Your buying power changes without you trading.** Because the requirement feeds the margin figures the API reports, `freeCollateral` falls at the RTH → off-hours boundary and recovers at the reopen, with no fill, transfer, or price move involved. Account equity itself is unaffected — only the collateral held against open positions changes. Don't treat a drop across the boundary as an error or a missed fill.
* **A position opened at max in-session leverage can sit below the off-hours initial-margin threshold.** That is expected and is **not** a liquidation trigger: liquidation is governed by maintenance margin, which does not move. The position stays open and can still be reduced or closed; what you cannot do until the session reopens is *open or increase* while below the higher requirement.
A per-account leverage override does not opt out of the uplift. The override is floored at the market requirement, so off-hours it can only ever raise your requirement, never hold it at the in-session level.
See [Trading when the underlying is closed](/concepts/perpetuals/real-world-assets#trading-when-the-underlying-is-closed) for the related funding and price-band behavior.
Exact off-hours margin multipliers and per-market requirements are part of each market's published parameters and may change. Always read the live values from the API rather than hard-coding them.
This documentation is built and hosted on [Mintlify](https://mintlify.com), a developer documentation platform.