For each perpetual contract, we use an index price which is the spot price of the asset on other exchanges. (Except XBTVIX index, which is calculated here).
For each perpetual listed below, we average the spot values across the following exchanges every second.
|Perpetuals||Spot Exchanges used in Index Calculation|
|XBTUSD||coinbase_pro, bitfinex, kraken, bitstamp|
|ETHUSD||coinbase_pro, bitfinex, kraken, bitstamp|