Why Do I Keep Breaking My Own Trading Rules?

What does breaking a rule actually cost?

Take a trader whose system produces +0.65R a trade — a 55% win rate at 2:1, which is a good system. Over 100 trades that is +65R.

Now let one trade in ten go off-plan: the stop gets moved, the size goes up, the loss gets held. Off-plan trades average −3R, because the whole point of the rule was to bound the loss.

• 90 trades on plan: 90 × 0.65 = +58.5R
• 10 trades off plan: 10 × −3 = −30R
• Total: +28.5R against +65R if every trade had followed the plan

Ten trades removed 36.5R, which is 56.2% of the year. This is why "mostly disciplined" is not a meaningful category — the exceptions are not distributed randomly across your trades, they cluster exactly where the rule was about to be expensive.

The direction of the breakage is well documented: traders sell winners readily and hold losers, a pattern named the disposition effect in 1985 and replicated many times since.^[1] Rules get broken asymmetrically, which is why "mostly disciplined" understates the damage.

Why do rules get broken?

Almost never by decision. The sequence is nearly always the same:

1. Price approaches the stop.
2. A reason appears — the level was arbitrary, the timeframe is longer than you thought, the news is stale, the market is "just testing".
3. The reason feels like new analysis rather than discomfort, because it arrives in the same voice your analysis arrives in.
4. The plan is updated. Not broken. Updated.

Step 4 is the failure, and it needs one specific condition to happen: the plan has to be revisable without leaving a trace. If the original stop is somewhere you cannot edit, step 2 still happens — the discomfort is real — but it now has to be argued against a fixed record instead of quietly overwriting it.

Does more willpower fix it?

Not durably, and betting on it has a worse record than any strategy you have tried. Willpower is lowest precisely when the position is against you, which is when the rule matters. Anything that requires you to be strongest at your weakest moment is designed backwards.

The alternative is to move the decision earlier, to a moment when nothing is at stake, and then make it costly to revisit. That is the whole logic of a commitment device, and it is why the stop belongs in the record rather than in your head.

What should be fixed before entry?

• The invalidation price — where the idea is wrong, not where the pain starts.
• Position size, computed from that distance rather than chosen from conviction.
• The target, or the rule that determines it — a trailing rule is fine, an open-ended one is not.
• What would make you exit early, stated in advance so it cannot be invented during the trade.

All four are cheap to decide before there is money on the line and nearly impossible to decide honestly afterwards. Sealing them is what stops the second decision from silently replacing the first.

Both halves are measured. Odean confirmed across 10,000 brokerage accounts that investors realise gains far more readily than losses,^[2] and prospect theory supplies the mechanism: outcomes are valued as gains and losses against a reference point, and people turn risk-seeking once they are behind.^[3] A rule is hardest to hold in exactly the state that makes breaking it feel reasonable.

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.