> For the complete documentation index, see [llms.txt](https://docs.nexus.xyz/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.nexus.xyz/exchange/usdx.md). # USDX **USDX is the Nexus Exchange's native margin and quote currency, pegged 1:1 to the US dollar.** Every market on the Exchange is denominated and margined in USDX, so traders hold a single collateral asset across spot and perpetual futures. ## What makes USDX different * **Yield on idle capital.** USDX earns yield from US Treasury bills on balances that aren't actively deployed — not from new token issuance or inflationary rewards. * **An exchange primitive.** USDX exists to make the Exchange work well for traders: one unified collateral and quote asset, composable with the EVM ecosystem on the Nexus blockchain. * **Backed and pegged 1:1 to USD.** ## What USDX is not USDX is not a standalone DeFi stablecoin protocol or a yield product. It is the collateral and quote layer of the Exchange. ## Learn more USDX backs every position on the Exchange — see [Margining](/exchange/trading/perpetuals/margining.md) for how collateral and leverage work, and [Quickstart](/exchange/trading/quickstart.md) to fund an account and place your first order. --- # 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.nexus.xyz/exchange/usdx.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.