Buying Power is the maximum value of new securities that may be purchased on the account.
Under the margin account , the maximum buying power is 4x the available funds, assuming a security has a margin requirement of 25%. However, each security has different margin requirements, and the buying power for each security should be calculated based on that security’s actual margin requirement, for details, please refer to the "Leverage" calculation method.
Margin account：maximum buying power = 4*Available Funds
Cash account：buying power = Available Funds