Normally, margin is a way to double your position size (as you put up half of the capital to buy a stock, and the broker puts up the other half.) However, a few weeks ago I bought $40,000 worth of a stock, and it only reduced my buying power by $10,000. This isnt intraday margin either, as this $10,000 buying power reduction has remained the case the entire time I've owned the stock. I checked the "securities with special margin list" but this stock is set at standard 50% margin requirement. I dont have enough money in the account to qualify for portfolio margin, so Im curious as to what is going on. Don't get me wrong, Im a fan. But just curious if Im understanding this correctly (that IB offers more leverage than other brokers) Or am I misunderstanding something.