Stop-Loss Placement: Structure, Volatility and Gaps

What you will learn

• The difference between structure-based and volatility-based stops.
• How to calculate a stop using the Average True Range (ATR).
• Why stops that are too tight often fail.
• Why gaps and slippage mean planned risk is not maximum possible loss.

Explanation

A stop-loss should sit at the price where your trade idea is proven wrong. It should not be chosen to make the position bigger. Decide the stop first, then calculate the size.

Structure-based stop: placed beyond a chart level that matters for your idea, such as below a recent swing low (a local low point) for a long trade. A small buffer is added because prices often briefly break such levels.

Volatility-based stop: placed a multiple of normal price movement away from entry. A common measure is the Average True Range (ATR). The true range of one bar (one period on the chart) is the largest of: high − low, |high − previous close|, |low − previous close|. ATR is the average of the true range over a number of bars, often 14. A stop at 1.5 × ATR or 2 × ATR is a typical starting point, not a rule.

Why too-tight stops fail: if the stop is inside normal price noise, ordinary movement hits it even when the idea is right. A tight stop allows a larger size, which looks attractive, but it lowers the win rate. Often it lowers expectancy too.

Gaps and slippage: a gap is a jump in price with no trading in between, for example from Friday's close to Monday's open. Slippage is the difference between your stop price and the price you actually get. A normal stop order becomes a market order when triggered, so it fills at the next available price. Your planned risk (1R) is therefore not the maximum possible loss. Some brokers offer guaranteed stops for a fee; check the conditions.

Worked example

Hypothetical example: account €10,000, risk €100. A share trades at €50. ATR(14) = €1.20. The most recent swing low is €48.10. Fees, spreads and taxes are excluded.

• ATR stop: 2 × €1.20 = €2.40 below entry → stop at €47.60.
• Structure stop: swing low €48.10 − buffer €0.30 → stop at €47.80 (risk €2.20).

Both methods give similar levels here, which is a good sign. Using the ATR stop:

Size = €100 ÷ €2.40 = 41.67 → 41 shares. Planned risk = 41 × €2.40 = €98.40.

Now assume bad company news overnight. The share opens at €45, below your stop. The stop fills at about €45.

Actual loss = 41 × (€50 − €45) = €205, which is about 2.05R. You planned to lose €100 and lost more than double.

Common mistake

Practice activity

Entry €120, ATR = €3, stop multiplier 1.5, risk budget €150. Calculate the stop price, the share size (whole shares) and the loss if the share gaps down to €110.

Key takeaways

• Place the stop where the idea is wrong, then size the position.
• ATR helps keep stops outside normal noise.
• Very tight stops raise the chance of being stopped out by ordinary movement.
• Gaps and slippage can make the actual loss larger than 1R.

Next step

Next you will learn how to manage a trade once it moves in your favour: targets, partial exits and trailing stops.