Stop-out levels and the slippage nobody models

[Amanhasnoname]

Margin stop-out looks like a clean rule: equity drops below a percentage of margin and positions get closed. The reality is messier, because the close happens at whatever price is available when the system acts.

On a heavily leveraged scalping account, the gap between the stop-out trigger and the actual close can be large during a fast move. Several positions closing in sequence also push price against the remaining ones, and the account can end below zero on brokers without negative balance protection.

The danger comes from stacking. Five positions each looking safe on their own can add up to a margin level that has no room for a single bad minute. News spikes and rollover widening make that worse, since spreads inflate the floating loss on every open trade at once.

A simple safeguard is to cap total margin usage at a number that survives a 20 to 30 pip adverse move across everything open at once. It sounds conservative until the day it matters.

What margin usage cap is considered safe for a scalping account, and does it change around news?