> For the complete documentation index, see [llms.txt](https://docs.sigsig.xyz/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.sigsig.xyz/core-concepts/futures.md). # Futures (Perpetuals) What perpetual futures are and how they track the market. A perpetual future ("perp") lets you trade the price of an asset without owning it and without an expiry date. * **Long** — you profit if the price goes up. * **Short** — you profit if the price goes down. ## How perps stay close to the spot price Because perps never expire, a **funding rate** keeps their price in line with the underlying market: * If the perp trades above the index price, longs pay shorts. * If it trades below, shorts pay longs. Funding is exchanged between traders at regular intervals. The symbol bar shows the current estimated rate and the countdown to the next payment. ## Mark price and index price * **Index price** — a reference price built from several external markets. * **Mark price** — the fair price used for unrealized PnL and liquidation. Using the mark price protects you from being liquidated by a short spike on a single venue. ## One position per market Each market holds one position per margin mode: your position is either long or short. Placing an order in the opposite direction reduces, closes or flips your existing position. Holding long and short on the same market at the same time (hedge mode) is not available yet. ## Liquidity Orders are matched on a central limit order book provided by [Orderly Network](https://orderly.network/). Liquidity is shared with other exchanges built on Orderly, which gives SigSig deeper books from day one. --- # 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://docs.sigsig.xyz/core-concepts/futures.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.