First off let me apologize if this is a stupid question. I heard that you if you withdraw more than the available funds you have in a brokerage account, that some brokerages will treat this as a margin loan and so are essentially loaning you money like a credit card company would do. I'm not saying I would do this, I'm just curious because this means that if the brokerage's margin loan interest rate is less than the credit card interest rate you could get, than you would be better off borrowing from the brokerage. Is this a common practice? I'm not sure if it's a stupid question or not because it never really occurred to me that people would do this given the relatively high margin interest rates.
If you have a long-term stock portfolio(Or investment grade corporate bonds) it can make sense to transfer those assets to a broker with low margin rates(Such as IB) then withdraw cash that you dont have, the difference will be a loan from IB. Call it the IB discount window, just make sure you dont get a margin call