Sun and Moon

Margin

The amount your broker holds from your balance to keep a position open.

It is not a fee or a loss - it is collateral, returned when the position closes. It follows from the contract size, the instrument's price and the leverage, so every extra lot holds more. Once margin ties up a large share of the balance the account is fragile to the first move against it, which is why sizing plans are built on a margin ceiling rather than on instinct.

Work it out on your balance