Pure Benchmarks · Definition
What Is a Decision Benchmark?
Short answer
A decision benchmark measures an investment decision against the alternative of not making it. At the moment you buy, sell or switch, it freezes the portfolio exactly as it stood and runs that do-nothing portfolio forward on real prices alongside your actual one. The gap between the two is what the decision was worth, in dollars and percent. An index benchmark tells you whether your whole portfolio beat the market; a decision benchmark tells you whether each change you made beat leaving things alone. Pure Benchmarks, our own product, uses the name Decision Benchmark for this measurement and calculates it automatically from linked accounts.
Most investment measurement answers one question: how did the portfolio do? A decision benchmark answers a different one: was the change I made better than not making it? That second question is the one most investors actually have after a sale, a switch or a rebalance, and almost no performance report answers it. This page defines the decision benchmark, explains how it is calculated, shows how it differs from index and peer benchmarks, and covers its limits.
The definition
A decision benchmark is the portfolio you would have held if you had not made a specific decision. It is built from your own holdings at the instant before the change, not from an index or a model, and carried forward on actual prices. Comparing your real portfolio with it isolates the effect of that one decision from everything the market did to both portfolios.
How it is calculated
At each buy, sell or switch, the holdings and quantities just before the trade are recorded. That frozen portfolio is then valued every day on real closing prices, with no further changes. Your actual portfolio is valued the same way. The difference between the two, measured from the decision date, is the decision’s result. Each later change creates its own benchmark, so every decision carries its own number.
How it differs from an index benchmark
An index benchmark compares the whole portfolio with a market index such as the S&P 500. It cannot say whether your shortfall came from your allocation, from the market, or from three changes you made last spring. A decision benchmark compares you with yourself, so the market drops out of the comparison and only the change remains.
How it differs from performance attribution
Classic performance attribution, such as Brinson attribution, splits a return against an index into allocation and selection effects by sector or asset class. It explains which parts of the portfolio carried the result. A decision benchmark is decision-level attribution: it explains whether a particular action was better than inaction, which is closer to how investors and advisors actually make changes.
What it can and cannot tell you
A decision benchmark shows the result of a decision so far, measured on real prices. It does not prove the decision was right or wrong in principle: a good decision can trail its benchmark for a while, and a poor one can lead by luck. Read across many decisions and over enough time, the pattern says far more than any single result. Pure Benchmarks, our own product, shows each decision’s result alongside a ranking against verified investors in the same risk category.
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See Your Free Benchmark ReportFrequently asked questions
What is a decision benchmark in investing?
It is the portfolio you would have had without a specific buy, sell or switch, carried forward on real prices. Comparing it with your actual portfolio shows what that decision was worth.
How is a decision benchmark different from a benchmark index?
An index benchmark compares your whole portfolio with the market. A decision benchmark compares your portfolio with your own pre-change portfolio, isolating the effect of each decision.
Is a decision benchmark the same as buy-and-hold?
It is a buy-and-hold counterfactual built from your own holdings at the moment of each decision, rather than a generic buy-and-hold index strategy.
Can a decision benchmark tell me if I am a good investor?
One decision cannot. A pattern across many decisions and different market conditions is much more informative. This page is information for comparison and not a recommendation about any holding.
Which tool calculates a decision benchmark?
Pure Benchmarks, our own product, calculates a Decision Benchmark for every change in linked brokerage and retirement accounts and reports the result in dollars and percent.
Keep exploring
- Did My Trading Beat Buy and Hold?
- What If I Had Done Nothing With My Portfolio?
- What Is a Buy-and-Hold Counterfactual Portfolio?
- How to Track Your Investment Decisions and Know Which Ones Were Best
- What Is My Real Portfolio Return After Deposits and Withdrawals?
- How Do Financial Advisors Benchmark Client Portfolios?
- What Is the Behavior Gap, and How Big Is Mine?
See how a specific firm's advisor decisions compare to other firms:
New here? Read the portfolio benchmarking FAQ or the Pure Benchmarks blog.
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.