A stop belongs at an invalidation price - below the swing low, outside the zone, past the level that would break the structure you traded. It does not belong at a round dollar amount you are comfortable losing, because the market has no interest in your comfort.
Once the stop is placed, position size is what controls the money at risk. Widen the stop and the correct size shrinks; that relationship is the whole of position sizing.
The mistake it causes: moving or removing a stop as price approaches it, which converts a planned small loss into the large one people remember for years.
The four places a stop can legitimately go
- Beyond a swing high or low. The structural level whose break means the trend you traded is no longer intact.
- Outside a zone. Past the far edge of the support or resistance area you entered against, with room for the wick.
- At an invalidation price. The level at which the specific reason for the trade stops being true.
- Beyond a volatility measure. A multiple of average true range, so the stop scales with how much the instrument is currently moving.
What is missing from that list is any dollar amount. A stop placed where the loss feels tolerable is placed by your comfort, and the market has no view on your comfort. Size the position so the structurally correct stop costs an acceptable amount instead, which is the job of the position size calculator.
Why stops get hunted
Resting stop orders cluster just beyond obvious levels and round numbers, and clusters of resting orders are liquidity. Price is drawn to liquidity. That is not a conspiracy against you personally; it is simply where the orders are. The practical defence is to place stops beyond the zone rather than at the exact line, and to accept a slightly wider stop with a correspondingly smaller position.
Stops are not guaranteed
A stop is an instruction to sell at market once a level trades. In a gap, a news spike or a weekend move, the fill can be far worse than the level you set - see slippage. Some brokers offer guaranteed stops for a fee. Where negative balance protection does not apply, a gap through your stop can leave the account below zero.
The mistake that costs the most
Moving a stop further away as price approaches it. It converts a planned small loss into the large one people remember for years, and it almost always happens for the same reason: the position was too big to lose comfortably, so the stop became negotiable. A correctly sized trade does not need its stop moved, because the planned loss was acceptable before the trade was taken.
