They key point that's missing here is that ALL stock trades are on "margin" because in reality it takes 2 days to settle a trade, but that is abstracted away fr

They key point that's missing here is that ALL stock trades are on "margin" because in reality it takes 2 days to settle a trade, but that is abstracted away from you by the brokerage and clearing house, and made available to you instantly. Caveat: I'm just starting to learn about all this, so it's probably not a perfectly accurate analogy.