Margin usage: the quiet number behind surprise stop-outs

[Shadow Trader]

Margin is the deposit the broker holds to keep positions open. Used margin divided by equity gives margin usage, and when it climbs too high, the cushion shrinks.

Scalpers who open several positions at once can burn through margin quickly. Each position locks a slice, and a sudden adverse move drains equity while margin stays locked. The margin level, which is equity divided by used margin, drops, and a stop-out may follow.

A good habit is to cap total margin usage at some fraction of equity, say ten or twenty percent, regardless of how much the broker allows. The extra room absorbs adverse moves and prevents forced liquidations at the worst prices.

Another detail: some brokers raise margin requirements before major news or over weekends, and positions held through those moments can suddenly breach the limits.

What's the maximum margin usage allowed by the trader's own rules, as opposed to the broker's?