What to record when you sell a stock

Here is a question that should bother you more than it does. You can probably recite, to the penny, what you sold a stock for last month. Now tell me why you sold it. Tell me what you expected when you did, and whether the thing that finally made you sell was the thing you swore in advance would make you sell. Silence? Thought so. The buy gets all the romance and all the research. Then the sell, the one moment that actually grades your homework, gets recorded as a single lonely number. The price. That’s the whole party, and it is a waste, so this is how you fix the most neglected habit in investing: knowing what to record when you sell a stock.

The sell is the lesson, not the buy

When you buy, you are guessing. A confident, well dressed guess, sure, but a guess. Nothing has happened yet. The market has not voted, your thesis is still a hopeful little essay, and the future is doing whatever it likes.

The sell is where the experiment ends and the results come in. Every assumption you made at the buy either survived contact with reality or got run over by it, and the sell is the moment you find out which. That is the best feedback your investing life will ever hand you. So what does most people’s standard practice do with it? Glance at the profit and loss, feel a little glow or a little sting, move on. You would never run a science experiment, get the result, and write down only “it cost forty quid”. Yet that is exactly what people do with the most expensive experiment they run all year.

Start with the actual reason you sold

The first thing to capture is the one everybody fudges. Why you sold. Not the price, the reason, and be honest about it.

There are only a few honest reasons to sell, and they are not created equal. The good ending is that your thesis played out and the position hit your target. Almost as good: an invalidation signal breached, the line you drew in advance got crossed, and you did the disciplined thing. Those are the two answers you want to see again and again, because both of them mean the plan ran the trade rather than your mood. The other reasons are worth catching red-handed. You got bored, or the price wobbled and your nerve went, or something shinier showed up. Writing down “I panicked” feels awful, and that is precisely why it is the most valuable line in the whole entry. Sort your sells by reason a year from now and the panic ones tend to share a sad little theme. You cannot fix a pattern you refused to name.

In Strata the sell asks you to say whether the thesis or an invalidation signal drove the exit, so the reason is structured data you can actually count, not a feeling you’ll have forgotten by Friday. If you want the longer argument for letting the signal pull the trigger instead of your gut, it lives in when to sell on an invalidation signal.

Capture the numbers your memory will lie about

Memory is a generous editor. It rounds your wins up and rewrites the plan so past-you looks like a genius, and it does this quietly, while you are not looking. That is why the numbers have to be written down at the moment of the sell, before the editing starts.

Realised P&L is the obvious one, and logging the sell is what produces it honestly. The trade closes your tax lots on a FIFO basis, your cost basis stays clean, and your gain is the real gain rather than a vibe. The number that teaches you more is realised R, your result measured in units of the risk you took. A win is just a win until you know whether you risked a little to make a lot or bet the house to scrape a small one. R is the thing that stops a small, sensible victory and a reckless near-miss from looking the same on the page.

Then there is the pair almost nobody keeps. MFE and MAE are the maximum the trade ran in your favour and the maximum it ran against you while you held it, and they quietly expose your exits. Forever leaving most of the move on the table because you bailed at the first green? MFE will rat you out. Sitting through stomach-churning drawdowns that worked out by luck? MAE has the receipts. Sitting on top of all of it is plan versus actual, which is what you said you would do at entry, your stop and your target, set against what you actually did. The gap between those two is your tuition bill, and you should at least read it.

Record how it felt, because that is half the trade

Now the unfashionable bit. Write down how you felt when you hit sell.

I know. Feelings, in a finance ledger, how soft. Except your feelings are not a sideshow to your returns. On a lot of trades they ARE the trade. The exit that torched your year was probably not a maths error. It was fear, or boredom, or the specific itch of watching someone else win. A journal that records only numbers is recording the evidence and burning the motive. So Strata’s journal carries an emotion scorecard, conviction, patience, discipline and that familiar demon FOMO, logged at the exit while the feeling is still warm and not yet laundered into a respectable story. String enough together and a face appears: maybe a disciplined holder who panics only in a particular kind of sell-off, maybe a patience that is immaculate until something shinier shows up. You cannot manage a habit you have never once looked at squarely.

Review it later, or none of this counts

Recording is only worth the effort if you go back and read it, which is the step that quietly dies in most people’s good intentions. A journal you never reopen is a diary, and a diary does not make you money.

The point of capturing the reason, the R, the MFE and MAE, the plan-versus-actual and the emotion scorecard is that it all becomes searchable evidence about one specific investor: you. Sort your sells by reason and the panic exits confess their average cost. Filter to the thesis-played-out wins and watch your real expectancy step out of the fog of feelings. This is the habit that powers a proper quarterly portfolio review. Reviewing the past you actually had is a far better edge than guessing at a future nobody has.

The checklist, and the honest catch

So here is the selling a stock checklist, in plain prose. The reason, named honestly. Whether your thesis or an invalidation signal drove it. Realised P&L with the tax lots closed. Realised R, so the win is measured against the risk. MFE and MAE, so your exit timing has nowhere to hide. Plan versus actual. And how it felt, before your memory tidies it up.

The honest catch is that this is manual. You type it, and Strata stays read-only and never touches your credentials, so the discipline is yours to keep. But that is the entire point. The price prints itself. The lesson only exists if you write it down. Do this for a few dozen sells and your selling stops being a nervous reflex and starts being a craft you are visibly getting better at. That is the feedback loop your money deserves, and you can start keeping it the next time you build your portfolio.