How to track a portfolio across multiple brokerage accounts

Here is a thought experiment that sounds easy and is secretly impossible. Right now, without logging into anything, say out loud the exact per cent of your net worth that sits in a single company. If your brain just returned a blurry shrug, you are not bad at this. You are being asked to read a book that has been scattered across a dozen rooms in the house: a brokerage, a second brokerage, a pension or two in their own sealed wing, a crypto exchange, a cold wallet you are slightly nervous about, and cash smeared across all of it like loose change down the back of every sofa.

Every account thinks it is the whole world

Each of those places shows you a lovely, confident dashboard, and every one is lying by omission. Not on purpose. A brokerage dashboard is just profoundly parochial: it shows that broker’s positions and that broker’s performance, because that is the entire universe as far as it knows. It has no idea you hold the same share two logins away, or that the cash earning nothing in your exchange account is part of the same decision as the bond fund three accounts over. (It is a bit like asking one ant about the colony and getting a very confident answer about the nearest four centimetres of tunnel.)

The wrappers make it worse. A taxable account, a pension and an exchange each report in their own frame, with their own basis rules and their own opinion about what counts as a gain. Stitching that into one picture is the chore that marches people off to a spreadsheet, or worse, to a credential-scraping aggregator that breaks in silence and leaves you unable to tell whether a doubled position is yours or the robot’s. We have written before about why we will never hold your brokerage logins to do this for you.

The expensive part is the part you cannot see

A scattered book hides exactly the things that cost you money. Start with concentration. The same share held in three accounts hides your true position size: you think you own a measured slice of one company, but across the whole book you are twice as exposed as you believe, and you find this out on the precise morning it gaps down. Allocation is the next domino. You cannot honestly say how much of your net worth sits in tech, or crypto, or cash, when the bottom of the fraction is split across five logins and the top is being double counted.

Cost basis is worse than it looks. Sell shares of a name you also hold elsewhere and your real gain depends on which lots, in which account, at which basis, which no single dashboard can work out, for the boring reason that none of them holds all the lots. Tax-lot accounting only works when every purchase of a security sits in one ledger that can order them, and realised profit and loss has the same problem.

And the headline number, your actual net worth, is simply not anywhere. No account knows about the others, so the grand total exists only as a wobbly estimate you assemble by logging into four places and adding them up. Which is the long way of saying you do not really know where you stand, a strange thing to accept about your own money.

Draw the whole map, once

Your instincts are probably screaming for more logins. Wrong direction. What you want is one book, entered a single time, in three unglamorous moves.

First, model each account as the thing it actually is. Create an account for every place you keep value: each taxable brokerage, each pension, the exchange, the wallet, the cash. The shape of your book should match reality, which is also what lets allocation and basis respect the boundaries that matter, like which holdings are sealed inside a tax-advantaged wrapper.

Second, enter the holdings and transactions per account, once. Most people hold a few dozen positions built up over years, not four hundred, so the entry is minutes per account, done one time. From then on the ledger is the system of record and you only append as you trade. And because you typed it, you can hold each account up against its own broker statement and know it reconciles, the one thing a scraped feed can never hand you.

Third, let the workbench derive the whole-book view. Once every account is modelled and every lot entered, consolidation falls out of the data. Strata sums your net worth across all accounts and asset classes, rolls every holding in the same security together so you see your true total size, and reports allocation by asset class across the entire book. FIFO tax lots and realised profit and loss are derived over everything at once, so basis is correct whether you bought a name in one account or three. Shares, ETFs, crypto, options and cash all land in the same reconciled picture. That is the whole map, finally on one screen.

It is the same idea underneath tracking a portfolio without surrendering your logins, which gets its own post: the linking was never the point. What you actually wanted was a reconciled book, and the only one worth trusting is the one you built yourself.

The map stays yours

Drawing the whole thing should not quietly cost you ownership of it. Strata never holds a brokerage login and never moves a penny. You enter the book, so the book is yours to audit. The ledger is immutable in the way an accountant’s is: mistakes are voided, flagged and excluded from the maths but never silently erased, and your holdings and cash are derived by replaying exactly what you entered, every change attributed and timestamped.

Instead of a number you cobbled together across five logins, you get one reconciled view of everything you own, derived from a ledger you control: true position sizes, real allocation, basis across the whole book, an honest net worth. The blurry shrug you started with now has a map where it used to be.