# Isolated margin All loans issued on hashstack are isolated margin loans. User has to choose the supply market along with their quantity to be used as collateral. Protocol then verifies the rTokens quantity to assure enough supply is pledged to use as collateral. These pledged rTokens cannot be transferred till loan is closed (We call this as locking rTokens). Only borrow contracts can lock/unlock the rTokens. --- # 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.hashstack.finance/hub/concepts/isolated-margin.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.