For most of the contacts listed on PrimeBit: stocks, indexes, precious metals, commodities, as well as BNBUSD and DOTUSD, we use the following formula:
Fair Price = Spot Price
For BTCUSD, BTCUSDT, ETHUSD, ETHUSDT, LTCUSD or LTCUSDT perpetual contracts we use the Funding Base rate to calculate the Fair Price, according to the following formula:
Fair Price = Spot Price x (1 + Funding Basis)
Where:
Funding Basis = Funding Rate x (Time Until Funding / Funding Interval)
Funding Rate (FR) = Premium Index (P) + clamp(Interest Rate (I) - Premium Index (P), 0.05%, -0.05%)
Time Until Funding - time remaining until next Funding
Funding Interval = 3 (since funding occurs every 8 hours)
Spot Price - average last price from multiple external crypto exchanges