# Oracle Prices

### Overview

For crypto assets Extended relies on Mark and Index Prices obtained from 5 nodes of an independent Oracle Provider, [Stork](https://www.stork.network/):

* Mark Prices are used to determine the liquidability of accounts and calculate positions' unrealized PnL.
* Index Prices are used for the calculation of Funding Payments. For detailed information on the calculation of Funding Payments, please refer to the section on [Funding Payments](/extended-resources/trading/funding-payments.md).

For a deeper understanding of the approach Stork employs to define Mark and Index Prices, explore Stork's comprehensive [documentation](https://docs.stork.network/).

Utilizing independent Oracle Providers like Stork helps prevent potential price manipulation and ensures an equitable and accurate reflection of asset values within the Extended ecosystem.

### Price Denomination

Both, Mark and Index Prices sourced from Stork are USD denominated. This means that on Extended USD PnL is settled in USDC given USDC margin.


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