Why Might You Be Charged More Margin?

If stocks bought under MTF are no longer on the approved list or if there is a margin shortfall, you could be asked to provide more margin in your account. If there is insufficient margin, the shares will be squared off 4 trading days after the shortfall occurs.
 
Factors that may lead to an increase in margin requirements include:
 
1. A drop in the price of collateral stocks.
2. An increase in the haircut (reduced value) of collateral stocks.
 
This difference in the margin available versus the required margin is known as an MTF shortfall.
 
Maintaining Margin:
 
To buy stocks through MTF, you must maintain sufficient margin, either in cash or collateral. If your stocks experience a loss or if the margin requirement increases, you may be asked to deposit additional funds into your account.