What a stop-out looks like when the market gaps through everything

[Shadow Trader]

Take an account long a currency pair with a stop-out level set at some percentage of margin. A shock arrives with no warning, the kind of event where liquidity disappears entirely. The Swiss franc peg removal in January 2015 is the textbook case: price moved enormously in minutes, and quotes were scarce.

The platform detects that margin level fell below the stop-out threshold and sends a closing order. But a stop-out is not a guaranteed exit at that threshold. It is a trigger that sends a market order, and a market order fills at whatever the market offers. If there are no bids near the old price, the close happens far below it.

That is how an account can end up with a negative balance. The loss exceeds the deposit because the closing price landed so far from where the stop-out was supposed to be. What happens next depends on the broker and the jurisdiction. Some offer negative balance protection and absorb the shortfall. Others reserve the right to ask for the difference. Regulation in some regions makes protection mandatory for retail clients, while elsewhere it is a matter of the broker's own terms.

So the line in the terms about negative balance is not boilerplate. It decides who carries the loss in the rare case that everything gaps at once.

Another detail worth checking is how stop-out is calculated. Some platforms use margin level percentage, others use equity relative to margin, and the order in which positions get closed can differ.

Has anyone actually checked their broker's negative balance clause, and what did it say about gaps and weekends?

[FXS Prop Desk]

So the line in the terms about negative balance is not boilerplate.

The franc case shows that a stop-out level is not a floor. Brokers close positions at the first available price, which in a gap can be far past the stop. Position size that survives that kind of gap is the real protection; negative balance protection in the account terms is the second line, and worth confirming in writing.