This call occurs when an account exceeds its available day trading buying power. If you receive a day trading margin call, your account will be on aggregation status. Aggregation status means the total cost of all day trades in one day cannot exceed your start- of- day buying power.
Example:
Start of day buying power $10,000
Purchase ABC ($5,000)
Sell ABC $5,000
Purchase XYZ ($5,000)
Sell XYZ $5,000
The total cost of the day trades is $10,000, so you cannot day trade until the next business day. If you were to place another day trade, a day- trading margin call would be generated.
More information on day-trading requirements can be found here.
