The short answer
A trading rule holds when three things are true: it is specific enough to check with a yes or a no, it was set before the session rather than during it, and something other than you enforces it. Most rule lists fail the third test. "Respect the stop" and "do not revenge trade" are written by a calm person on a Sunday and broken by a different person on a Tuesday, in one click, with nobody watching. The fix is not more rules or more resolve. It is five rules, each one a number, each written as an if-then plan, each decided before the open, and as many as possible handed to something that will not negotiate: a resting order, a limit at the broker, a person, or software that closes the platform.
Why do traders break their own rules?
Because the moment a rule matters is the moment you least resemble the person who wrote it. A loss changes what the next trade is for. Odean's study of 10,000 brokerage accounts found investors far more willing to sell winners than losers, which is the same instinct that drags a stop further away: taking the loss makes it real, and not taking it keeps the hope alive. The mechanics of that are covered in why you keep trading past your limit.
The second reason is cost. Breaking a trading rule is free and instant. There is no form, no delay and no witness. Any rule that depends on you choosing correctly, every time, in that state, at that price, will eventually lose.
What makes a rule hold?
Two pieces of research are worth more than any list of tips.
The first is about wording. Gollwitzer and Sheeran pooled 94 independent tests of what they call implementation intentions, plans in the form "if situation X arises, then I will do Y". Compared with holding the goal alone, the if-then form had a medium-to-large effect on whether people did the thing. The reason given is that the decision has already been made; when the situation arrives there is nothing left to deliberate.
The second is about who enforces. Ariely and Wertenbroch asked whether people will set themselves costly deadlines, whether those deadlines help, and whether people set them well. The answers were yes, yes and no: self-imposed deadlines improved performance, but were not as effective as some deadlines imposed from outside. People know they need constraints and are not very good at setting their own.
Put together: write the rule as if-then, and move the "then" out of your hands wherever you can.
Which five rules?
These five cover most of the ways an account is lost. Each has a number you choose and a place the enforcing can live.
| Rule | As an if-then plan | Where the enforcing can live |
|---|---|---|
| Risk per trade | If the stop distance times the size is more than my R, then the size comes down before I enter | Sizing worked out from the stop, before the order |
| Daily loss limit | If I am down my daily number, then the day is over | A limit at the broker, a person, or software that closes the platform |
| Trade count | If I have taken my number of trades, then the day is over | A counter you cannot reset |
| The stop | If I am in a position, then a stop order is resting at the broker, and it only ever moves toward my entry | A real order, not a mental one |
| Stand-down | If I lose two in a row, then I stop for the day | The same thing that enforces the daily limit |
How to choose the numbers, with the arithmetic, is in risk management for day traders. The free loss budget and position size calculator does the division. For the trade count alone, how to stop overtrading shows how to find the number from your own record.
Notice what is not on the list: nothing about entries, indicators or which way to trade. Those belong in a playbook. Rules are about what you will not do regardless of what the chart says.
How do you set trading rules so you cannot argue with them?
Set them before the open and treat them as frozen until the close. The one allowed change is tightening. If the morning goes badly and you want a smaller limit, take it. Loosening waits until tomorrow, when the person deciding is the calm one again.
Write the consequence in the morning too. "If I reach the limit" needs a "then" that has already been chosen, because a limit whose consequence is decided at the limit is decided by the wrong person. There are four honest options: only count it, warn me, end the day, or end the day and make the platform unavailable. Any of them is fine if it is chosen in advance. The first is useful for a month of measuring; the last is for the trader who already knows what the trade after the limit looks like.
What enforces a rule when you will not?
In rough order of strength.
- A resting order. A stop at the broker fires whether or not you are looking. A mental stop is a plan to make a decision later. A stop the broker refused is not resting either: why Robinhood rejects a stop on the wrong side of the price is the commonest way that happens.
- A limit the broker holds. Some brokers and every prop firm will enforce a daily number for you. What Interactive Brokers does and does not offer an individual account is set out in how to set a daily loss limit on Interactive Brokers.
- A person. Someone who sees your rules-kept number every week. Harkin and colleagues found that monitoring progress worked better when the record was reported to someone than when it was kept private.
- Software that removes the option. Something that closes the platform at the limit and keeps it closed.
- Friction. If nothing else, a delay: stand up, leave the room, ten minutes by a clock. It is the weakest of the five and still better than nothing.
Willpower is not on the list. It is what all five are there to replace.
How do you know the rules are working?
Count them. For each trade, was each rule kept, yes or no; the fields to record are in what to write in a trading journal. Rules kept as a percentage of trades is the first number in a weekly review, ahead of profit, because it is the one you fully control. A week where the number went up and the account went down is a better week than the reverse, and the next hundred trades will usually show why.
Where Degen Pro fits
Degen Pro is a Mac app for Interactive Brokers that holds these five rules so that you do not have to. Before the open you set the daily budget per instrument, the trade count and how many reds in a row end the day, two unless you say otherwise, and you choose what happens on the trade after the limit: just count it, warn me, end the day, or end the day and lock the broker. Once armed the terms are frozen; you can tighten them during the day and loosen them tomorrow. The lock closes Trader Workstation and TradingView and holds them shut until the next morning. Position size is worked out from the stop and the budget, not from the last trade. The stop is a real order at the broker; the app never loosens it and puts it back if you cancel it by hand. Every trade is marked for rules kept and whether it was planned, and the week is summed up on a card with rules kept, grades and R and no dollar figure. It gives no signals and never opens a position on its own. It needs a Mac, and Interactive Brokers for the stop and the lock. It cannot make you write good rules, and it makes no promise about your results.
Write them tonight
Five lines, each with a number, each starting with "if". Decide the consequence of the daily limit now. Tell one person what the five are. Then trade twenty days and count how often each was kept before changing any of them.
None of this is investment advice. Trading involves risk of loss, and rules limit the damage without removing it.