Pure Benchmarks · Definition
What Is a Buy-and-Hold Counterfactual Portfolio?
Short answer
A buy-and-hold counterfactual is the portfolio you would have today if you had stopped trading at a chosen point and simply held what you owned. It is the fairest test of whether your trading added value, because it starts from your own holdings and faces exactly the same market. If your actual portfolio is ahead of the counterfactual, your changes helped over that period; if it is behind, doing nothing would have been better. Building one by hand means recording holdings at each change and revaluing them on historical prices, which is why few investors ever see theirs.
Asking whether your trading beat the market mixes two things: how the market did and what your trades did. A counterfactual separates them by asking what would have happened to the same starting portfolio without the trades. This page explains what a buy-and-hold counterfactual is, how to build one, why it is a fairer test than an index, and what to watch for when reading the result.
Counterfactual means the road not taken
A counterfactual is the outcome of the choice you did not make. In investing, the most useful one is usually inaction: the same holdings, in the same quantities, left untouched. Because it holds what you held, it carries the same sectors, the same concentrations and the same risk at the starting point, which makes it a like-for-like comparison.
How to build one
Record your holdings and share counts at the starting date or just before a change. Value those shares on each later date using historical closing prices, including dividends if you reinvest them. Compare that value with your actual portfolio, after removing any deposits and withdrawals from the actual side. Repeating this for each change gives a separate counterfactual for every decision.
Why it beats an index for judging trades
An index holds different things from you, so beating or trailing it reflects your allocation as much as your trades. A buy-and-hold counterfactual starts from your own holdings, so the only difference between the two portfolios is what you changed. DALBAR’s investor behaviour research has repeatedly found that average investors trail the funds they own, with 2024 showing a gap of 848 basis points, largely from the timing of buys and sells; a counterfactual shows whether that gap applies to you.
What to watch for
A counterfactual measures results over a window, and short windows are dominated by noise. Deposits and withdrawals must be handled consistently, or new money looks like trading gains. Taxes and trading costs are real and should be considered alongside the result. And a counterfactual says what happened, not what should have been expected when you made the decision.
Getting one automatically
Pure Benchmarks, our own product, builds a buy-and-hold counterfactual, which it calls the Decision Benchmark, at every change in linked accounts and runs it forward on real prices, so each trading decision carries a dollar result against having left the portfolio alone.
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See Your Free Benchmark ReportFrequently asked questions
What is a counterfactual portfolio?
It is the portfolio you would have had under a different choice, most usefully the choice not to trade. It starts from your own holdings and faces the same market.
How do I know if my trading beat buy and hold?
Compare your actual portfolio, with deposits and withdrawals removed, against the counterfactual built from your holdings before the trades, over the same dates.
Why not just compare my portfolio to the S&P 500?
An index holds different things from you, so the comparison mixes your allocation with your trading. A counterfactual isolates the trading.
Does a counterfactual include dividends?
It should, if you reinvest them in practice. Otherwise the comparison understates the do-nothing portfolio.
Is there a tool that builds a buy-and-hold counterfactual for me?
Pure Benchmarks, our own product, builds one at every change in linked accounts. This page is information for comparison and not a recommendation about any holding.
Keep exploring
- What Is a Decision Benchmark?
- Did My Trading Beat Buy and Hold?
- What If I Had Done Nothing With My Portfolio?
- Am I Trading Too Much? How to Tell If Your Trades Add Anything
- How Do Financial Advisors Benchmark Client Portfolios?
- What Is the Behavior Gap, and How Big Is Mine?
- What Is Outcome Bias, and How Does It Distort My Investment Decisions?
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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.