You can choose to use the pre-market, post-market, and overnight prices to calculate the market value and P/L of your position for the pre-market, post-market, and overnight trading hours, respectively. If you choose not to use them, the closing price for the regular trading hours will be used by default. (Special Note: If you do not use the overnight price, but select the post-market price, then during the overnight trading hours, the closing price for the post-market hours will apply before 12:00 AM ET, and the closing price for the regular trading hours will be used after 12:00 AM ET.)
In addition, if you choose to use the overnight price, your Today's P/L will be reset at 8:00 PM ET every day. You can also check your Yesterday‘s P/L. Futu calculates your Yesterday‘s P/L from 8:00 PM to 12:00 AM ET.