Why Do I Move My Stop Loss, and What Does It Cost?

What does one moved stop cost?

Take a trade risking $200 to make $400, with a 55% win rate. Expectancy is 0.55 × $400 − 0.45 × $200 = $130 a trade.

Now move the stop once the trade goes against you, so the risk becomes $400 while the target stays at $400. Same entry, same target, same win rate. Expectancy is 0.55 × $400 − 0.45 × $400 = $40.

Notice what did not change. Same entry, same target, same hit rate — nothing you would describe to another trader as your strategy. The only number you touched was the stop, and it was carrying more than two thirds of what the trade was worth.

That is the part worth sitting with, because it explains why the habit survives. Traders file the entry under skill and the stop under housekeeping, so the stop is the one number they feel entitled to revise once the position is open. It is the most valuable number in the trade and the only one anybody renegotiates mid-trade, and those two facts are not a coincidence — you are permitted to edit it precisely because you have mislabelled what it does.

This is the disposition effect, one of the most replicated findings in the literature: investors realise gains far more readily than losses.^[1] Moving a stop is that reluctance expressed as an action.

How good would you have to become to break even on that?

The win rate that restores $130 against a $400 risk and a $400 target is 66.25%.

So you would have to go from being right 55% of the time to being right 66.3% of the time — an 11.25-point improvement in raw forecasting skill — purely to undo one habit. That is the comparison worth keeping: nobody improves their hit rate by eleven points, and traders spend whole careers chasing one or two. Almost everyone can stop moving stops this week. The cheap fix is not the modest option here, it is the one with the better expected return.

Why does it feel like the right call at the time?

Because the alternative is a certain loss and the edit converts it into an uncertain one, and humans reliably prefer that trade even when it is worse in expectation. Two other things help:

• It works often enough to be reinforced. At a 55% win rate, price comes back more than half the time you widen. The habit is trained by its successes and the failures arrive as one large loss much later.
• The new stop always has a reason. There is a level slightly below, and it genuinely is a level. The analysis is not fabricated; it is selected, which is much harder to notice.

What actually stops it?

Making the original stop something other than a number in your own notes. Once the invalidation price is sealed before the fact, widening it is not an amendment to a private plan. The earlier number still exists and still says what it said.

Is widening a stop ever correct?

Yes, and the honest version of this page has to say so. If the initial stop was set inside the instrument's normal noise — inside its average daily range, or inside a spread on an illiquid option — then the trade was mis-sized from the start and the correct fix is a smaller position with a wider stop, decided before entry. What is never correct is discovering that mid-trade, while the position is open and losing, because at that moment you cannot tell the analysis from the discomfort. Size the trade so the stop can sit where the idea is actually wrong.

Shefrin and Statman named the pattern in 1985 — winners sold too early, losers ridden too long^[2] — and prospect theory explains why the second half happens: relative to a reference point, people become risk-seeking over losses.^[3] Widening a stop is that disposition converted into an order.

kappi is a trade recorder: you commit a trade before the fact, it is sealed on your device for a time-capsuled delay you choose, then kappi publishes it on a Merkle-anchored log. The seal is the whole mechanism — once a stop, a target and a thesis are sealed, revising them is no longer a private edit. $15/month, no free tier.

Note what that does not require: no willpower at the moment of maximum discomfort, no promise to yourself, no accountability partner watching the screen. The earlier decision simply survives, and surviving is the entire function.