# External Custody ## **Overview** Deri Protocol adopts a money market protocol as "external custodian" to carry out the following functionalities: * Holds and secures user capital in one or several base tokens; * Calculates a total dynamic effective value of the user capital deposited. ## AAVE: The Money Market Protocol on Abitrum For the trading business to better scale, Deri Protocol adopts AAVE as the external custodian on Abitrum. AAVE does not just hold capital but also calculates its dynamic effective value. The support of multiple base tokens is more systematical, as users can choose to deposit any token supported by AAVE, e.g. USDC, DAI, WBTC, ETH, LINK. When users deposit several kinds of tokens, the real-time total dynamic effective value of the tokens is calculated by AAVE with some built-in functions. --- # 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://docs.deri.io/how-it-works/external-custody.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.