# Index Price The Everstrike Index Price is an artifical price that Everstrike derives from an average of real time prices from a collection of Spot exchanges. The purpose of the Everstrike Index Price is to aid in the calculation of the [Everstrike Mark Price](/trading/mark-price.md). The Spot exchanges that contribute to the average can be seen below. To prevent price manipulation, 75% of the prices are treated as outliers, and removed from the average. The Index Price is updated at a fixed interval - currently every second. Spot Exchanges that currently contribute to the Everstrike Index Price: * Kraken * Coinbase Pro * Binance * Bitfinex * Kucoin * Huobi * Gate.io * Bitget * Okx * Crypto.com An Index Price is calculated for each derivatives contract on Everstrike. For perpetual options, the Everstrike Index Price is the Intrinsic Value of the option (based on the Everstrike Index Price of the perpetual futures contract for the option's Underlier). If the intrinsic value of the option is zero, the Everstrike Index Price will default to 0.05% of the Everstrike Index Price of the futures contract of the Underlier. --- # Agent Instructions: Querying This Documentation If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question. Perform an HTTP GET request on the current page URL with the `ask` query parameter: ``` GET https://references.everstrike.io/trading/index-price.md?ask= ``` The question should be specific, self-contained, and written in natural language. The response will contain a direct answer to the question and relevant excerpts and sources from the documentation. Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.