This section focuses on index calculation for underlying assets, referenced in the contract specifications as 'Thalex BTCUSD' and 'Thalex ETHUSD'. In what follows we will refer to either as "Index".

Each Index is computed based on order book data for spot markets from a number of exchanges. The calculation has four steps:

1. Obtain a list of prices from constituent exchanges. The price of an exchange is calculated as the average of best bid and ask in the order book.
2. Calculate the median of available prices.
3. Cap each price to deviate at most 0.5% from the median.
4. Calculate the simple average of capped values to obtain the Index.

Shown as a formula with available exchange prices denoted as