# Perpetual Future Mark Price Index

The perp index price is a volume-weighted perp price across supported exchanges, converted from USDT to

**USDC**using a volume-weighted average of USDC-USDT and BUSD-USDT spot markets.- Exchanges: Binance, ByBit, OKX
- Markets: Markets quoted in USDT and converted to USDC using volume-weighted spot price for USDC-USDT and BUSD-USDT markets
- Volume: trailing four (4) hours trailing volume for each perp market

For any asset where Stork provides a mark price, it is calculated as follows:

$Mark Price_{t} = \frac{\sum_{i=1}^{n} Perp Price_{it} \cdot Weight_{it}}{USDT/USDC_{t}}$

where:

- PerpPrice(it): Price of asset on exchange i at time t
- Weight(it): 4-hour trailing trade volume for perp on exchange i as of time t

and:

$USDT/USDC_{t} = \frac{\sum_{i=1}^{n}c_{it} \cdot v_{it}}{\sum_{i=i}^{n}v_{it}}$

where:

- c(it): the spot price for spot USDC/USDT market (or BUSD/USDT market on Binance) on exchange i at time t
- v(it): 4-hour trailing volume for spot USDC/USDT market (or BUSD/USDT market on Binance) on exchange i

*Note that unlike the index price, every Stork publisher follows the same calculation for the perp index price.*

Last modified 2mo ago