Leverage, margin and total exposure: the risk you can't see

Leverage is the most misunderstood topic in retail trading. Some people hear "high leverage" and think "high risk"; others blame it for every blown account. In reality leverage sets how much margin the broker holds back, not how much you can lose on a single trade: that's decided by the risk you set with your stop and lot size. The real danger of leverage is something else: it lets you open positions far bigger than your account, and that's where disasters start.

Margin and leverage

When you open a position, the broker holds part of your balance as margin (a deposit as collateral). The margin required depends on the position's value (the notional) and the leverage:

Margin = notional ÷ leverage

Higher leverage frees up margin, so you can do more things at once (including getting more things wrong). For retail clients in Europe, regulated brokers apply leverage limits (for instance 1:30 on major currency pairs) precisely to reduce the damage; where leverage is far higher, the client is usually registered with an entity outside those protections.

Margin level and stop out

The broker constantly watches your margin level:

Margin level = equity ÷ used margin × 100

Equity is your balance plus the profit or loss on open positions. When the level falls below a threshold (margin call) the broker warns you; below an even lower one (stop out) it starts closing your positions, usually the biggest loser first, whether you like it or not. The thresholds depend on the broker, so look up your account conditions: they differ from one broker to the next.

If you respect your risk per trade and don't pile on too many positions, you'll never get anywhere near these levels. If you see them, it's almost always because you opened too much, too close together or too correlated.

Total exposure

A 1% risk rule applies to one trade. But if you have three trades open at once, each risking 1%, you have 3% of your account in play. And if the three trades are correlated, the real risk can be close to that of a single big trade.

Two practical rules:

• Total open risk: set a cap on the sum of risks across open positions (for example 3% for a cautious account) and never go over it.
• One idea per currency: if you already have a big exposure on one currency (say, long the dollar), don't stack more trades on the same idea, unless you split the risk between them.

Positions that grow

Another trap is adding size while a trade is in profit, or averaging down (adding) on one that's losing. Adding to a winner can make sense if total risk stays within your limits and your stop moves to protect you. Adding to a loser means raising the bet on an idea the market is rejecting: it's one of the most common ways accounts get blown.

Leverage as a way of life

A simple rule: your effective leverage (total notional ÷ account) should stay low. If with $10,000 you hold positions worth $200,000 in notional, your effective leverage is 20: a 5% move against you wipes out the account, even if the broker's maximum leverage is far higher. Working out your effective leverage tells you how exposed you really are.

In short

• Margin is collateral: notional ÷ leverage. Leverage doesn't change a trade's maximum loss, it changes the margin tied up.
• The danger of leverage is opening positions that are too big, or too many at once.
• Margin level decides whether the broker closes your positions: with proper risk management you'll never see it.
• Add up the risks of your open positions, allowing for correlation, and set a cap.

Practice

1. Work out the margin required for 0.50 lots of EUR/USD at 1.08 with 1:30 and 1:200 leverage.
2. List the pairs in your portfolio and, for each, which currency you're buying and which you're selling. Do any overlap?
3. Write the total open-risk cap for your plan.