No, IBKR will not automatically convert proceeds from sell orders into your base currency. If you sell securities denominated in a different currency, the proceeds will remain in that currency. You can manually convert the proceeds back to your base currency if desired.
Example: If you place a sell order for a US stock and your base currency is in GBP, the proceeds will remain in GBP. You will need to manually convert the USD to GBP if you want the funds in your base currency.
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