Option Buying Power vs Day Trading Buying Power
It is possible that a customer’s Option buying power (BP) will be different from his Starting Day Trading BP at the start of the day. The reason for this is that Option BP is derived by using the lesser of maintenance excess or concentrated (House) excess. Day trading BP is calculated using Federal Reserve (Fed) minimum excess. House margin requirement rules do not affect day trading BP. In many cases starting day trading buying power will be higher than option BP.
Note: When Option BP is less than starting day trading BP, the system will not let a customer exceed the Option BP when placing a trade.