> For the complete documentation index, see [llms.txt](https://whitepaper.nomoex.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://whitepaper.nomoex.com/our-product/nomodex/overview-of-perpetual-futures/index-price.md). # Index Price **What is Index Price?** The index price is based on the latest transaction price of the standard currency pair of the mainstream exchange in the market and the median buy-to-sell median, weighted average, calculated and obtained index price, which can represent the fair market price of the currency pair. **Index Exception Handling** **Removing Invalid Prices:** If any source exchange price is not updated within 40 seconds and significantly deviates from the previous value, we consider it not valid and reset the price for that pair to zero. **Abnormal Price Correction:** When an exchange's price deviates from other exchanges by ±3% of the median deviation of all source exchange prices (including itself), we recalculate its price to the median ±3% of the remaining exchange prices. For example, if the USDT median deviation reaches ±3%, we recalculate that exchange's price to the median ±3% of the sample. This mitigates outliers and ensures index price integrity by adjusting excessively deviating prices. --- # Agent Instructions This documentation is published with GitBook. GitBook is the documentation platform designed so that both humans and AI agents can read, navigate, and reason over technical content effectively. Learn more at gitbook.com. ## 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, and the optional `goal` query parameter: ``` GET https://whitepaper.nomoex.com/our-product/nomodex/overview-of-perpetual-futures/index-price.md?ask=&goal= ``` `ask` is the immediate question: it should be specific, self-contained, and written in natural language. `goal` is optional and describes the broader end goal you are ultimately trying to accomplish on behalf of the user. GitBook uses it to tailor the answer towards what is most useful for that goal. 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.