Okay, I have an etrade account and they let me have 4x my account value for intraday margin purchasing power. So for example, if i have 100k, then i have 400k buying power. My question is that if i hold positions at any point during the day totaling over 100k, would i get charged interest if i never carry those positions overnight (essentially intraday trading)? So i would be buying stocks and selling them before the day ends. Also, would i ever get a margin call if i always liquidate my positions before the market closes? Thanks.