# Margin Collateral Risks Ethena uses both linear and inverse margined perpetual futures, using linear perpetual futures that are denominated in USDT. Denominating in Tether means that the margin and PNL calculations are quoted in Tether, and by extension, results in Ethena being positionally long USDT. For example, if Ethena posts BTC as margin collateral, and takes a short position on a linear BTC/USDT perpetual future - Ethena has a delta of 0 on BTC due to being long spot (collateral) and short futures (perpetual), but it is directionally long USDT (quote currency) with no offsetting short exposure. The inherent risk this presents is exposure to a potential USDT idiosyncratic event. For context, 80% of perpetual futures open interest is stablecoin-margined, with the vast majority of those quoted in USDT. Ethena closely monitors USDT stablecoin price risk and solvency, and if a problem persists will take action accordingly. In this instance, Ethena would aim to move more of the perpetual futures positions into inverse contracts, margined with BTC or ETH, depending on liquidity. --- # 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.ethena.fi/solution-overview/risks/margin-collateral-risks.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.