Here is a breakdown of why a stop-out can still occur even when your net exposure is zero.
If your account equity falls below the required threshold relative to your used margin, the system will automatically close positions to protect the account from a negative balance.
The Result: Even if the mid-price hasn't moved, the widened spread can push your equity low enough to hit the stop-out level.
Holding positions overnight incurs swap or rollover charges. These fees are deducted from your account balance/equity daily. Over time, these costs can slowly erode your equity. If you are already trading with high leverage or low free margin, these daily charges can eventually push your margin level below the stop-out trigger.
It is a misconception that a hedge requires zero margin. 25% of margin is still required for both sides of the trade. If your equity fluctuates—even slightly—due to price gaps or volatility, you may no longer meet the margin obligations for those open positions.
We recommend that you always maintain a healthy "buffer" of free margin in your account, even when hedged, to account for spread fluctuations and financing fees.