Portfolio tracker spreadsheet vs app: when your spreadsheet starts to lie

Let me guess how your portfolio tracking began. One spreadsheet, a column for tickers, a column for what you paid, a sneaky formula pulling live prices, and a gain column that goes green when you feel clever. No app, no subscription, nobody holding your broker login. You built the thing yourself and you understand every cell in it.

And do you know what? Good for you. That is the right instinct, and I am not here to talk you out of it. I am here for the slightly sad afternoon when your spreadsheet quietly stops telling you the truth and lets you believe a number that is wrong.

The spreadsheet is genuinely fine, until it isn’t

A spreadsheet gives you the two things that actually matter: control and ownership. Every formula is right there in front of you, and you can see how the gain column is calculated because you are the muppet who wrote it. No pipeline slurping your accounts, no third party clutching your brokerage password, no mystery service deciding what your book is worth this morning. The data lives in a file that belongs to you. That is most of the point.

For a small book in one currency, a dozen positions you bought once and barely touch, a grid is plenty. The maths is just arithmetic, and arithmetic does not need a monthly fee. Anyone telling you to abandon a perfectly good spreadsheet at this stage is selling something. The spreadsheet is the correct tool right up until the book outgrows it, and nobody rings a bell on the day that happens.

The afternoon it starts lying to your face

The break is never a satisfying crash. What you get instead is drift, a slow trickle of tiny wrongnesses that no cell flashes red about, because cells do not have feelings and will report nonsense with total confidence.

Here is the usual rogues’ gallery. Your live-price formula coughs and returns a blank, or last Tuesday’s number, or an error code that a SUM three rows down cheerfully treats as zero, and your net worth is now fiction with nothing turned red. A stock splits and your share count is half what your broker says. A spinoff drops a new line into your account that exists nowhere in your sheet. A reinvested dividend quietly nudges your share count and cost basis, so your yield and basis both wander off. One position starts trading in another currency and every total now leans on a rate you typed in by hand and forgot about in March. And tax lots are where the sheet truly gives up the ghost: hold the same ticker in a taxable account and a pension and the lots have to stay separate and ordered, but your spreadsheet will happily average them into one number that is simply, quietly wrong.

Notice the pattern? None of this throws an error. The sheet keeps computing. You end up with a book you can no longer reconcile against your statements, dressed up with all the swagger of a number in a cell.

The trade-off everyone gets wrong

Here is where the usual advice falls over. The choice gets framed as control versus convenience, as if you have to hand back your freedom to get a tool that does the sums for you. That framing is daft, because most portfolio apps make you trade away the exact thing you liked about the spreadsheet. They want your brokerage login so a robot can sign in as you, and a scraped book breaks silently too: positions double or vanish, and you cannot tell whether you fat-fingered something or the pipeline did. You have swapped a sheet you understood for a feed you cannot audit. There is a whole separate rant about why handing over your bank login is bananas, and I will spare you it here.

So the real trade-off was never control versus convenience. The thing wearing you down is upkeep, and the cure is derivation. The spreadsheet quietly conscripts you as its calculation engine. You patch the price formula, you hand-adjust for the split, you re-key the FX rate, every weekend in instalments, and every manual touch is one more chance to fat-finger a silent error into a book you are trying to trust. The work grows as your book grows. You have built yourself a part-time job you did not apply for and do not get paid for.

Keep the control. Bin the weekend ritual.

Here is the bit nobody told you was on the menu. Keep typing in your own data, because that is what gives you a ledger that is genuinely yours and a book you can reconcile. But stop being the calculation engine. You record the transactions, and the software derives everything downstream.

That is the whole idea Strata is built on. Lots and cash are derived by replaying the ledger you entered, so a correction never leaves stale rubbish behind. FIFO tax lots, realised profit and loss, dividends, multi-currency valuation and factor scores all fall out of one reconciled book, across every account and asset class, with the same ticker in three accounts treated as a single position instead of three rows you keep in sync by prayer. Splits and dividends are events you log, not formulas you nurse, and a mistake gets voided and kept in the history rather than silently overwritten. This goes double the moment your book sprawls across several brokerage accounts. Manual entry here is the entire design, not a grudging limitation, and it comes from the same instinct that made you reach for a spreadsheet in the first place. Own your data. See how the numbers are made. The maths is the computer’s problem now.

So here is your tell. The day you start double-checking your own spreadsheet against your statements before you believe it, it has stopped being an asset and become a rumour. Keep the part you loved, the ownership, and hand the drudgery to something that never gets bored and never fat-fingers a SUM on a Tuesday.

Your spreadsheet served you well. Let it retire with dignity.