Pure Benchmarks · Guide

Investment Decision Journal: What to Record and How to Review It

Short answer

An investment journal is only useful if each entry is written before the decision and makes the decision gradable later. The core fields are: what you are buying or selling and why, what you expect to happen and over what period, what would prove you wrong, how much you are prepared to lose, how you feel at that moment, and what you would do with the money instead. That last field supplies the alternative you will compare the result against. At review, grade two things separately: whether the reasoning was sound, and whether the decision beat the alternative.

Professional investors have long used decision journals for one reason: memory rewrites decisions. Once an outcome is known, the reasoning that led to it gets reshaped to fit, and good luck is remembered as skill. A written entry made before the decision is the only record that cannot be edited by hindsight. This page sets out the fields that make an entry useful, how often to review, how to grade decisions separately from outcomes, and how to fill the gap for decisions you already made before starting a journal.

The fields to record before each decision

Date and action: what you are buying, selling, or holding, how much, and at what price. Thesis: the specific reason, in one or two sentences. Expectation: what you think will happen and over what time horizon. Disconfirming evidence: what would prove the thesis wrong. Risk: how much you are willing to lose and what you will do if that happens. Alternative: what you would do with this money otherwise. State of mind: whether you feel excited, anxious, rushed, or calm. The alternative and the disconfirming evidence are the two fields most people skip and the two that make an entry gradable.

The fields to record at review

Outcome: the return since the decision. Result against the alternative: how the decision compared with what you wrote down you would have done otherwise, or with doing nothing at all. Thesis check: whether what happened matched what you expected, and for the reasons you expected. Decision grade: whether the reasoning was sound given what you knew, recorded separately from whether it made money. Lesson: one sentence on what you would do differently.

Grade the decision and the outcome separately

A good decision can lose money and a bad one can make it. A holding can rise 30 percent on a market rally while the thesis was completely wrong. If you only record the outcome, the journal teaches outcome bias. Keeping two grades, one for the reasoning and one for the result, is what turns a journal from a diary into a tool. Over time the useful pattern is where the two grades disagree, because that is where luck has been hiding.

How often to review

Review each entry when the position closes, and review the whole journal on a fixed schedule, such as every quarter, regardless of what markets are doing. Reviewing only after big moves biases the sample toward dramatic decisions. The patterns worth finding tend to be in the ordinary ones: a sector you keep misjudging, a habit of selling after drops, or a tendency to buy on news.

The gap a journal cannot fill

A journal only covers decisions made after you start it, and most are abandoned within months. For everything before that, the transaction history is the record. Rebuilding the portfolio as it stood before each past change and pricing it forward gives the do-nothing comparison that the alternative field would have supplied. Pure Benchmarks, our own product, does that from connected holdings through Decision Benchmark, which pairs naturally with a journal: the journal records the reasoning, the counterfactual measures the result.

Your current platform won't show you how your portfolio ranks against real investors in the same risk category. Create your secure Pure Benchmarks account and see exactly where you stand.

See Your Free Benchmark Report

Frequently asked questions

What should an investment journal include?

For each decision: the action and price, the thesis, the expected outcome and time horizon, what would prove you wrong, how much you are willing to lose, what you would do with the money instead, and your state of mind. At review: the outcome, the result against the alternative, whether the thesis played out as expected, and a separate grade on decision quality.

Why keep an investment decision journal?

Because memory rewrites decisions once outcomes are known. A written entry made before the decision is the only record hindsight cannot edit, and it lets you separate the quality of your reasoning from luck.

How do I review my investment decisions?

At a fixed interval, grade each decision on two separate scales: whether the reasoning was sound given what you knew, and whether the result beat the alternative you recorded. Look for patterns where the two grades disagree, because that is where luck has been mistaken for skill or the reverse.

Can I evaluate decisions I made before starting a journal?

Yes, using your transaction history. Rebuild the portfolio as it stood before each change and price it forward on real historical data to see what doing nothing would have produced. Pure Benchmarks, our own product, automates that from connected holdings.

Is there an app for tracking investment decisions?

Journaling can be done in any notes app or spreadsheet. Tools that measure decisions differ in method: some report money-weighted returns and contribution analysis, some compare against an index or model portfolio, and Pure Benchmarks, our own product, compares each decision against the do-nothing version of your own portfolio. The attribution tools comparison on this site sets out the differences.

Keep exploring

See how a specific firm's advisor decisions compare to other firms:

New here? Read the portfolio benchmarking FAQ or the Pure Benchmarks blog.

This page is an information baseline for comparison only. It is not investment advice and not a recommendation to buy, sell, replace, or transfer any specific asset, account, or firm. Past performance does not guarantee future results. All figures shown are illustrative.