One of the components used to help calculate our Mark Price is the Phemex Index price. To view, check out What is the Mark Price and Dual Pricing mechanism?
Phemex BTC indices are sourced from the last traded prices of multiple spot markets. These include: Binance, Bitstamp, Coinbase, Huobi, Kraken, and OKEx. Phemex also obtains its USDT/USD rate from Binance and so on, in order to adjust prices quoted in USDT.
Every time Phemex computes an index, it begins by removing the highest and lowest last traded prices found amongst these 6 exchanges. The final index price is the average value of the remaining last traded prices. The Phemex index engine refreshes and publishes new indices every second.
In addition, Phemex excludes and invalidates sources with broken connections or updates that have stalled for more than 15 seconds. At any given time, the index engine requires at least 3 valid sources to compute an average price. If the number of valid sources drops below 3, the index price will remain unchanged.