The amount of stock required to be closed when the account is in a margin deficit depends on the account type and the open positions held in the account. For example, if you have a Reg T margin account and have an SMA deficit of USD -1,000 USD, you will need to close USD 2,000 of marginable stock to get SMA back to zero and make the account Reg T compliant. For a USD -1,000 deficit in a Portfolio Margin account (assuming all stock positions have a margin requirement of 15%), you will need to close approximately USD 6,700 of marginable stock. Please note, open positions in your account can have different margin requirements, so we recommend using the Check Margin Impact feature to preview the change in the account's margin requirements before submitting an order. Review the amount in the "Change" column to see if an order will increase or decrease the account's total Maintenance Margin requirements.
For more information, please visit the IBKR's User’s Guide or the IBKR Knowledge Base.