Day Trade Buying Power (Day Trade BP) refers to the buying power available in your account that can be used specifically for placing day trades. Day Trade Buying Power is calculated every day prior to the market opening. The calculation is 4 times your margin excess based on the previous day’s closing prices. Some securities may have higher day trading requirements than others. If you exceed your Day Trade Buying Power, a day trade call will be issued. Day trade calls can only be met by depositing funds.