Risk & Money Management · Beginner · 5 min
Placing a stop-loss sensibly
You can place a stop where the trade idea is proven wrong, not at an arbitrary distance, and explain the limits of stops in gaps.
Where does the stop go?
Ask ten beginners where they place their stop, and many will say: wherever the loss feels bearable. A little below the entry, so it does not hurt too much.
The market does not know what feels bearable to you. A stop placed by feeling is either hit by ordinary price movement, or so far away that the loss is far larger than planned. There is a better way to decide.
Where the idea fails
A stop-loss is a planned exit for a trade that goes against you. In practice it is usually a stop order, as covered in the lesson on order types: once the price reaches a level, the order is sent to close the position.
The key question is where to put it. A sensible stop sits at the invalidation level: the price at which your reason for the trade is proven wrong. Every trade has an idea behind it, for example "buyers defend this low" or "the range will break upward". The stop belongs just beyond the point where that idea clearly fails.
In the chart, the price fell to 48.60, where buyers stepped in and pushed it back up. A trader who buys at 50.40 because "the low at 48.60 holds" has a clear invalidation level: a fall below 48.60. The stop goes a little below it, at 48.40, to leave room for small overshoots.
Two more rules make stops work:
- Outside the noise. Prices move up and down all the time. A stop inside that normal movement is hit by chance, even when the idea is right.
- Size follows the stop. If the sensible stop is far away, take a smaller position, so that the loss in money still fits your percent-risk rule. Never move the stop closer just to make the position bigger.
Stops have limits too. The SEC explains that a stop order becomes a market order once triggered. In fast markets or after a gap, for example overnight or after news, the next available price can be well beyond the stop, and the loss larger than planned.
Right idea, stop in the noise
Two fictional traders buy the same share at 50.40, after the bounce from 48.60.
- Trader A places the stop at 50.00, only 0.40 below the entry, because a small loss feels safer.
- Trader B places the stop at 48.40, below the low that the trade idea depends on.
Two candles later, the price dips to 49.90 before rising to 51.80. Trader A is stopped out at 50.00 for a loss, then watches the trade work without them. Trader B's stop is never touched.
Trader B's stop is five times further away, so B buys a fifth of the size to keep the same risk in money. The loss if wrong is the same for both. Only B's stop had a real reason to be where it was.
Common mistakes
- Stops at round distances. "Always 1% below entry" ignores what the chart says.
- Stops exactly at the obvious low. Leave a small buffer beyond it.
- Moving the stop further away during the trade. That turns a planned loss into an open-ended one.
- Believing a stop guarantees the price. Gaps and fast markets can fill it worse.
The takeaway
Place the stop where your trade idea is proven wrong, not where the loss feels comfortable. Then size the position to fit.
Check yourself
Quick quiz
4 questions. Instant feedback, nothing is saved.
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1Tap the low that the stop is placed below.
Tap the chart.
The swing low at 48.60 is where buyers stepped in. If price falls below it, the idea that the low holds is proven wrong.
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2What is the main idea behind a sensible stop?
The chart decides where the idea fails. The position size then decides how much that costs.
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3Why can a stop be filled worse than its price?
The SEC notes that a stop order becomes a market order once triggered, and the fill can differ from the stop price, especially in gaps.
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4A stop sits just 0.10 below the entry, inside the normal up-and-down of the price. What is the likely result?
A stop inside the normal range of the price gets triggered by random movement. Give it room, then reduce the size.
of 4 correct.