How to Place a Stop Loss: 3 Methods That Work

Step 2 of 6 in Trading Foundations.

A stop loss marks the price at which your trade idea is wrong. That is the whole definition — and it explains why the most common approach, "I can only afford to lose $200, so I will put the stop $200 away", produces such poor results. The market has no interest in your account size.

Place the stop from the chart first. Size the position second.

Method 1: structure stops

Put the stop just beyond the price level that would invalidate the setup — the swing low you bounced from, the range boundary you broke out of, the moving average you are trading above.

If you buy a pullback to support at $48.20 because you believe support holds, then a trade below $48.20 says it did not. The stop belongs a little under it, say $47.90, with the buffer sized to the instrument's normal noise.

Structure stops are the most logical of the three because the exit level means something. Their weakness is inconsistency: sometimes the nearest structure is 0.5% away and sometimes 6%, which makes position sizes swing wildly.

Buffer the level, do not sit on it. Stops resting exactly at an obvious swing low are the easiest liquidity in the market. Give it room — a fraction of the ATR, or a few ticks past the wick.

Method 2: ATR (volatility) stops

Average True Range measures how far the instrument typically travels in a period. An ATR stop places the exit a multiple of that distance from entry, so the stop automatically widens in fast markets and tightens in quiet ones.

Stop = entry − (ATR × multiplier) for a long.

With an entry at $100 and a 14-period ATR of $2.50, a 2× multiplier puts the stop at $95.00 — a $5.00 per-share risk. On a $10,000 account risking 1% ($100), that sizes the position at 20 shares.

Tighter multipliers buy a bigger position and a higher chance of being stopped out by noise. Wider ones survive the noise at the cost of size. Most swing setups sit between 1.5× and 3×; intraday work often runs tighter.

Method 3: percentage stops

The simplest version: exit if price moves a fixed percentage against you — 5%, 8%, whatever the strategy specifies.

Percentage stops are easy to apply consistently and require no chart reading, which is why long-term and systematic investors use them. The trade-off is that they are volatility-blind. An 8% stop is loose on a utility stock and tight on a small-cap biotech, so the same rule produces very different stop-out rates across a portfolio.

If you use them, at least scale the percentage by asset class rather than applying one number to everything.

Which to use

In practice many traders combine the first two: find the structural level, then require it to be at least 1× ATR away, and take the wider of the two.

Four things that ruin an otherwise good stop

Moving it wider. Widening a stop as price approaches converts a planned 1% loss into an unplanned 5% one. If the level is wrong, the trade is over — take the loss and re-enter if the setup re-forms.

Placing it at a round number. $50.00, 1.2000, 5000.00 — these attract resting orders and get probed. Sit a little beyond them.

Ignoring the spread. A stop is triggered by the bid on a long position. On a wide-spread instrument, a stop placed at the last traded price is already closer than you think. Add the spread to the buffer.

Forgetting gap risk. Stops are not guarantees. Holding through earnings, a central bank decision or a weekend means the fill can be far past your level. Size down when you know an event is coming.