Where can I monitor my available margin?
The usable margin column in the accounts window of the Trading Station shows the amount of funds you have remaining in your account to open new positions or guard against losses. There are two things that can decrease your usable margin: opening new positions and sustaining losses on existing open positions.
If the usable margin reaches $0, a margin call is triggered due to insufficient funds to maintain any of the open positions.
The Trading Station displays how much margin has been set aside for existing open positions. The information is located in the "Accounts" window in the column titled "Usd Mr" (Used Margin).