# Borrow

Collateralized lending refers to the process where users mortgage inscription assets to borrow $sUSD on the Shell Finance platform. The lending operation is completed in a single transaction without transferring assets to any trusted third party. Currently, Shell Finance supports assets, including BTC, Ordinals, Runes, BRC-20, and Atomics protocol. It evaluates collateral value based on real-time quotes&#x20;

provided by a price oracle and calculates the loanable amount based on the preset loan-to-value ratio. For example, if a user uses the BRC-20 asset $ORDI as collateral, valued at 1000 USD, they can borrow $sUSD, valued at 600 USD, after paying certain loan and Gas fees.

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As illustrated, when a borrower initiates a loan request, the process is as follows:

* Shell Finance requests the market price of $ORDI from Apro Oracle to calculate the maximum loanable amount and the loan-to-value ratio.
* Shell Finance constructs a Partially Signed Bitcoin Transaction (PSBT) based on the loan amount and associated protocol fees, completing the signing process.
* Shell Finance adds the borrower's collateral details and the output of the collateral in the vault to the PSBT, presenting the final result to the borrower for verification. Simultaneously, Shell Finance calculates the liquidation price based on the loan amount and requests Apro Oracle to initiate a Discrete Log Contract (DLC).
* After the borrower verifies all the data and finds it consistent with what is displayed on the page, they can sign the loan transaction to finalize it.

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