Pure Benchmarks · Guide

What If I Had Done Nothing With My Portfolio?

Short answer

Take your holdings as they stood on the date in question, apply no trades, and price them forward to today on real end-of-day data. That is the do-nothing portfolio. Comparing it against what you actually own isolates the value of every decision you made in between, which a total return figure cannot do because it fuses the market, your deposits and your trading into one number.

It is the question that arrives after a trade goes badly, and it is usually unanswerable, because the portfolio you gave up stopped existing the moment you changed it. Your broker shows you what you own now. Nobody keeps the version you walked away from. Reconstructing it is not guesswork though; it is an ordinary calculation, provided you still know exactly what you held and can price those holdings forward. This page covers how to run it, the two mistakes that make the answer wrong, and what the result does and does not prove.

What the calculation is

Pick a date. Take the exact holdings and quantities you owned on that date. Apply none of the changes you made afterwards. Price those positions forward to today using real end-of-day data, crediting dividends as they were paid and adjusting for any splits. The value you land on is what doing nothing would have produced. Comparing that against your actual portfolio today gives you the dollar value of everything you did in between.

Mistake one: ignoring the cash

A sale you never made is cash that never arrived. A purchase you never made is cash that was never spent. The do-nothing portfolio therefore carries a different cash balance than the real one from the moment of the first change onward, and that cash has to be tracked, not assumed away. Comparisons that quietly drop the cash leg produce a gap that can point in either direction depending on which trades you happened to make.

Mistake two: counting deposits as performance

If you paid money in after the starting date, your real portfolio is larger for a reason unrelated to any decision. Treating that as outperformance turns your savings rate into a skill score. The comparison has to neutralise external money on both sides, which means measuring the return of each version rather than subtracting one ending balance from the other.

What the answer proves, and what it does not

A do-nothing portfolio that beat you means those specific changes, over that specific window, cost money. It does not establish that trading is always wrong, that the changes were unreasonable when you made them, or that the pattern will repeat. One window is one sample. What makes the number useful is repetition: the same measurement applied to every change over years turns an anecdote into a track record.

Doing nothing is not the same as doing nothing well

A portfolio left completely alone drifts. Winners grow into a larger share, the mix gets riskier, and the allocation you chose is not the allocation you end up with. So the honest version of this question is usually not whether you should have frozen everything forever, but whether the specific changes you made beat the specific alternative of leaving them alone over that period. Those are answerable one decision at a time.

Making it automatic

Running this by hand once is tedious but possible. Running it for every change you make, indefinitely, is not, which is why most investors never learn whether their decisions work. Pure Benchmarks, our own product, keeps the portfolio you left behind at each change and carries it forward automatically, so the comparison exists without anyone rebuilding it. It requires a read-only brokerage connection and only measures decisions made after the account is linked, because it cannot reconstruct holdings it never saw.

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Frequently asked questions

What would my portfolio be worth if I had never traded?

Take the holdings you owned on your chosen starting date, apply no subsequent trades, and price them forward to today on real end-of-day data including dividends and splits. That figure is your do-nothing value. It is a definite number rather than an estimate, as long as you know the exact positions you started from.

Does doing nothing usually beat trading?

Often, but not always, and the honest answer for your portfolio is specific to your portfolio. Industry studies of average investor behaviour consistently show a gap between fund returns and investor returns caused by timing. That is an average across many people and says nothing definitive about your own decisions, which is exactly why measuring yours is worth doing rather than assuming.

How is this different from comparing myself to the S&P 500?

The index is an outside portfolio you never owned, holding companies you may not hold, at weights you did not choose. The do-nothing portfolio is your own holdings with your decisions removed. Comparing against the index measures whether you kept up with the market; comparing against doing nothing measures whether your decisions added anything.

Can I work this out myself in a spreadsheet?

Yes, for a single decision, if you have the exact holdings before the change and a source of historical prices. It becomes impractical across many decisions and multiple accounts, mainly because of the cash tracking and the dividend and split adjustments, which is where hand-built versions usually go wrong.

What if my advisor made the changes rather than me?

The same calculation applies and the result is more actionable, because it is the measurable part of what the advice was worth. Freeze the portfolio before each change the advisor made, run it forward, and read the gap net of the fee you paid over that period.

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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.