Shares in the US take 3 days to settle. Technically when you buy a share, and it shows up in your account you don’t have actually own it. The broker is only sho

Shares in the US take 3 days to settle. Technically when you buy a share, and it shows up in your account you don’t have actually own it. The broker is only showing you what you expect to receive. Same for selling a share. Cash from the proceeds will show up in your account, but the broker hasn’t actually received that money from the settlement. You can trade with that cash, only because the broker is extending you credit. This is why you can’t trade more than once every three days in an IRA. Tax exempt accounts can’t be used as collateral for loans.