# Trading Support

Use this page for common order, margin, and liquidation questions.

## Why Was My Margin Pool Liquidated?

Liquidation uses the oracle mark, not the last trade.

Meridian calculates risk for one quote-token margin pool:

* Cross-margin positions with the same quote token share risk.
* An isolated product has a separate synthetic quote-token pool.
* A different subaccount or quote-token pool does not support the liquidated pool.

Equity can decrease because of an adverse mark, funding, position fees, trading fees, or realized losses. See [Liquidations](/trading/perpetual-futures/liquidations).

## Why Is Available Balance Lower Than Total Balance?

Available balance excludes amounts that support current risk. These amounts can include:

* Initial margin for open positions.
* Margin reserved for open orders.
* Unrealized losses.
* Outstanding funding.
* Outstanding position fees.

Unrealized profit does not increase available margin for a new order or withdrawal. Close or reduce a position, cancel an order, or add collateral to increase available balance.

See [Margining](/trading/perpetual-futures/margining).

## Why Did My Limit Order Not Fill?

A limit order fills only at its price or a better price. It can remain open if the market moves away or if other orders have priority.

A limit order can also have a partial fill. The remaining quantity stays open until it fills, expires, or is canceled.

## Why Did My Market Order Have Slippage?

A market order uses available order-book prices. A large order can fill at several price levels. Price and liquidity can also change before the execution block is processed.

The mark, last trade, best bid or ask, and final execution price are different values.

## Why Did a Stop Trigger at a Different Fill Price?

A stop uses the oracle mark as its trigger. After the trigger, a stop-market order uses the order book. The trigger price is not a guaranteed fill price.

During an mPerp mark-price gap, the mark is frozen. The stop can remain inactive until a fresh mark arrives. A gap at reopen can cause substantial slippage. See [Mutualized Perps](/trading/perpetual-futures/rwa-perpetuals).

## Why Was a Limit Order Charged as Taker?

A limit order is taker liquidity if it crosses an order that is already on the book. Use post-only behavior if the order must add liquidity.

## Why Does the HTTP Response Show Zero Filled?

Taker orders wait in the execution block. Therefore, the immediate placement response has `filled: "0"`. Use WebSocket order and fill streams for the actual result.

See [Block Execution](/trading/perpetual-futures/block-execution).

## Still Need Help?

Visit [app.meridian.xyz](https://app.meridian.xyz) and use the support control. Never send a seed phrase, private key, or recovery code to support staff.