What is mark price and index price in futures?
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The index price is the reference price of the coin taken from spot markets. The mark price is based on the index price and the last futures price, and it is the price Xoibit uses for your unrealized PnL, margin ratio, liquidation and TP/SL.
The three prices on the futures page
- Last price: the price of the latest trade on the futures market. This is what most charts show.
- Index price: the reference price of the coin, from the spot market on Xoibit or from external exchanges.
- Mark price: a price based on the index price and the last price.
Why use the mark price?
The last price can jump for a moment when a single large order hits a thin order book. Because the mark price also follows the index price, it is steadier, so a short spike on one market is less likely to liquidate positions or trigger stop losses unfairly.
What is the mark price used for?
- Unrealized PnL and ROI of your open positions.
- Margin ratio and therefore liquidation.
- Take profit and stop loss triggers.
- Funding fees: the position value at mark price is used to calculate the fee.
- Limit price bands: limit orders must be within a cap and floor around the mark price.
What is my entry price then?
Your entry price is the average price your orders actually filled at. Your PnL is the difference between the entry price and the mark price, times your position size.
When the last price and the mark price are far apart, your PnL, liquidation price and TP/SL can behave differently from what the chart shows. Always look at the mark price on the trading page.
常问问题
Why is my PnL different from what the chart shows?
PnL uses the mark price, while the chart usually shows the last price.
Why didn't my stop loss trigger when the price touched it?
TP/SL trigger on the mark price, not the last price.