What is Perpetuals mark price?
Mark price is the fair price for perpetuals market to calculate unsettled P&L of positions and generate real-time funding rates.
Calculation of mark price
BIT's mark price is derived from both the index price and the fair price as follows:
Mark Price = Index Price + 30 seconds EMA* of (Fair Price - Index Price)
*EMA: An exponential moving average (EMA) is a type of moving average (MA) that places a greater weight on the most recent data points. The exponential moving average is also referred to as the exponentially weighted moving average.
Fair Price = (Fair Impact Bid + Fair Impact Ask) / 2
Fair Impact Bid = The average price at which Impact Notional worth of contracts can be bought
Fair Impact Ask = The average price at which Impact Notional worth of contracts can be sold
Impact Notional is used to determine how deep in the order book to measure the Fair Impact Bid/Ask price. The Impact Notional amount is set to be, e.g. 10,000USD for BTCUSD Perp, 3,000USD for BCHUSD Perp, and in the range of 1,000 to 3,000USD for other USD-Margined contracts.
Fair Price can never be 5% higher than the best ask or 5% lower than the best bid, and Mark Price is limited within 0.5% from Index Price against manipulative trading.
The Impact Notional and price limits might be adjusted by the BIT risk team according to market conditions.
How to check the mark price
Mark price is slightly different from index price, you could track the real-time mark price on the top of the contract trading page.