回复：Maybe different brokers have different policies. I

Thank you for your reply. I am with Scottrade too. To make it clear,For example, I sold MSN Monday, and use the sale to buy apple, and then sell apple and buy apple again. This is not allowed with cash account. I have position MSN at the open market and have apple when market is closed. Under the cash account, definitely, I have a free ride. My question is under margin account, if I sell apple on Tuesday, am I going to be charged one day interest then because the settlement day is Thursday and I sell it before the settlement day.