Mark price and price index are two crucial concepts used to determine the valuation and settlement price of contracts. These concepts may vary across different trading platforms and contract types, so it is essential to refer to the specific platform's documentation and rules to understand their definitions and calculation methods.

1. Mark Price:

   • The mark price is a reference price used to calculate contract profit and loss (PNL) and liquidation levels. It is typically determined based on the exchange's specified algorithm or price index and is used to assess traders' margin levels and liquidation prices.
   • The calculation of the mark price may incorporate the following factors:
     • The price index of the contract trading pair
     • Market depth and liquidity
     • Leverage and position size
     • The platform's risk management mechanisms
   • By using the mark price, exchanges can reduce the manipulation of contract prices and the impact of market volatility on traders, thereby providing a fairer and more stable trading environment.

2. Price Index:

   • The price index is a reference indicator used to calculate the mark price. It is typically derived from the trading data of multiple exchanges or markets to provide an impartial, accurate, and reliable price reference.
   • The price index can be calculated using weighted averages, medians, or other algorithms to reflect the true market conditions. Its purpose is to avoid excessive influence of abnormal prices from a single exchange or market on the contract price, thus providing a more stable and reliable mark price.
   • It is important to note that different exchanges and contract platforms may have different price indices and calculation methods. Therefore, when participating in coin-margined contract trading, it is advisable to thoroughly understand the exchange's definitions and calculation rules and to comprehend and accept the sources and calculation methods of its price index before trading.

In summary, the mark price and price index play a critical role in coin-margined contracts, determining the contract's valuation, calculating PNL, and liquidation prices. Understanding the exchange's rules and mechanisms and closely monitoring changes in the mark price and price index are crucial for contract traders.