How-to
How to keep an investment research journal
An investment research journal is a running record of what you buy and sell, why, and what you expected, kept so you can learn from your own decisions instead of your memory of them. Write each entry at the moment you act, while your reasoning is honest and unedited by the outcome. Record the decision, the thesis in a sentence, what you expected, and what would change your mind. Note how you felt, because emotion drives most bad trades. Then revisit old entries and compare what happened to what you predicted. Over time the pattern in your own mistakes teaches you more than any single win.
By The Brief Equity Team · Published
What should you record?
| What to record | Why it matters |
|---|---|
| The decision | The what, when, and price you can check against later |
| The reason | Your thesis in your own words, not the company's |
| What you expected | The prediction you will grade yourself against |
| How you felt | Emotion, not analysis, drives most bad trades |
| Your exit test | The facts that would change your mind, set in advance |
The entries people skip are the emotional ones, and those are the most valuable. Recording that you bought in a hurry because the stock was running, or sold in a panic on a red day, builds a record of your own tendencies that no amount of market knowledge replaces.
Write the change-my-mind facts before the position moves. Written after a loss, they are just rationalization. Written before, they are a genuine test.
How do you actually keep one?
- Write the entry at the moment of the decision, not later. Memory rewrites itself.
- Date every entry and tie it to the ticker.
- Keep it short. A paragraph you will reread beats a page you will not.
- Revisit old entries on a schedule and compare outcome to expectation.
- Note what you got wrong plainly. The mistakes are the point.
The single rule that matters is timing: write at the moment of the decision. Hindsight quietly edits your memory of why you acted, so an entry written a week later is already contaminated by what happened since.
Keep it short enough that you will actually do it. A journal you maintain for a month and abandon teaches you nothing; a spare paragraph per decision that you keep for years is worth a great deal.
How do other investors journal their decisions?
Many serious investors keep a decision journal to fight hindsight bias. You record the reasoning before the outcome is known, so later you can judge the decision on its logic rather than its result. A good process can lose money and a bad one can get lucky. The journal keeps the two separate.
The idea traces back to decision-making research long before it reached investing: judge the decision by what you knew at the time, not by how it turned out. Markets are noisy enough that good decisions lose and bad ones win often, so outcome alone is a poor teacher.
Where should the journal sit?
A journal only works if it sits where you research. Brief Equity gives each stock a notebook, so a decision log sits next to the price, the feed, and your thesis. Write an entry the moment you act, link it to the note that holds your reasoning, and reread both when you revisit the position.
A separate journal app is one more place to forget. Keeping the log beside the research means that when a position moves, your original entry and the note behind it are right there, and revisiting is a matter of scrolling, not searching.
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Frequently asked questions
- What should I write in an investment journal?
- The decision, your reasoning in a sentence or two, what you expected to happen, how you felt, and the facts that would change your mind. Set the last one down before the position moves, while it is an honest test rather than a rationalization.
- When should I write a journal entry?
- At the moment you make the decision, not later. Hindsight quietly rewrites your memory of why you acted, so an entry written after the fact records the story you tell yourself, not the reasoning you actually used.
- Should I record how I felt about a trade?
- Yes. Emotion, not analysis, drives most bad trades, and a record of when you acted out of greed, fear, or boredom is one of the most useful things a journal gives you. It exposes patterns no market data will.
- How often should I review my journal?
- Revisit an entry when the position next reports, and do a broader read a few times a year. Comparing what happened to what you predicted is where the learning is; an unread journal is just a diary.