Do investors really underperform their own funds? The famous number is disputed.

Most articles quote the first half. The second half is the interesting one.

What the gap is

Two different ways of measuring a fund's return:

• Total return — what the fund earned, holding from start to finish. What appears on the fact sheet.
• Dollar-weighted return — what the average dollar actually earned, accounting for when money arrived and left.

If investors add money after a run and withdraw after a fall, the dollar-weighted return comes in below the total return. That difference is the gap.

Morningstar's figures for the decade through 2024: 8.2% total, 7.0% dollar-weighted, a 1.2-point annual shortfall. They've found gaps of similar size for the ten-year periods ending 2020, 2021, 2022 and 2023 — the persistence is a big part of why the finding is taken seriously.

The critique — and why it's credible

Fulkerson, Jordan, Riley and Yan's paper is called, bluntly, "Bad Timing Does Not Cost Investors 15% of Their Funds' Returns." Their argument, simplified:

Dollar-weighted returns are sensitive to the shape of cash flows, not only to their timing skill. A fund that grows steadily — because the asset class is growing, or because a strategy is being adopted over time — will mechanically show a gap even if no individual investor ever mistimed anything. Money simply arrived later, so less of it was present for the earlier returns.

Aggregating across funds compounds this. So a meaningful portion of the measured gap reflects the arithmetic of growing asset bases, not investors panicking.

This is a real methodological objection published in a peer-reviewed journal, not a marketing rebuttal. Anyone citing the 15% figure should know it exists.

What survives the disagreement

Here's the thing: the critique narrows the number, it doesn't eliminate the phenomenon. Both sides agree that timing-driven shortfalls appear, and that they are worst in exactly the places you'd predict.

Morningstar's consistent finding across editions is that the gap is largest in the most volatile categories — sector funds, thematic funds, anything with dramatic performance swings — and smallest in broad, boring allocation funds that people buy and forget. Their own summary of the pattern is direct: the more investors traded, the less the average dollar made.

That distribution is very hard to explain by cash-flow arithmetic alone. If the gap were purely mechanical, it wouldn't concentrate in the funds that most invite emotional trading.

So the defensible version is:

• ✅ Investors in volatile, exciting funds tend to earn meaningfully less than those funds report
• ✅ The effect is persistent across measurement periods
• ✅ Trading frequency is associated with worse dollar-weighted outcomes
• ⚠️ "The average investor loses 15% of their returns to emotion" is a stronger claim than the data cleanly supports

Why this matters more than the exact number

Whether the true figure is 1.2 points, 0.5, or somewhere between, the practical instruction is identical and it isn't complicated:

The gap, whatever its size, is created by discretionary decisions made during volatility. Nobody underperforms their own fund by holding it. You get there by adding after it ran, or trimming after it fell, or switching to whatever performed better last year.

Which means the fix is mechanical, not intellectual:

• Automate contributions so they can't be reconsidered during a decline
• Prefer boring, broad funds if you know you're reactive — the gap is smallest there for a reason
• Write your rules before volatility, because the decision has to be made by the calm version of you
• Reduce checking frequency; nothing you see intraday should change a multi-year plan

If that sounds like what to do when the market drops, it's the same underlying problem wearing different clothes.

The uncomfortable implication

Notice what the debate is really about. Nobody disputes that some investors destroy returns through timing. The argument is about how much, on average, across everyone.

But you are not the average. You're one person with a specific pattern of behavior under stress, and the population average tells you nothing about which side of it you fall on. Some investors have essentially no gap. Some have a large one.

The only way to find out which you are is to observe your own decisions under pressure and grade them — which is why we score every trade Brilliant, Good, Inaccuracy, Mistake, or Blunder on the reasoning at the time, and why the Time Machine lets you generate the pressure on purpose instead of waiting years for a bear market to test you with real savings.

FAQ

What is the investor return gap?

It's the difference between a fund's reported total return and the dollar-weighted return actually experienced by investors, which accounts for when money was invested and withdrawn. Morningstar's 2025 study found a 1.2 percentage point annual gap for US funds over the ten years to December 2024 — 8.2% fund return versus 7.0% investor return.

Do investors really lose 15% of their returns to bad timing?

That framing is disputed. Morningstar's 1.2-point annual gap equates to roughly 15% of total returns, but a 2026 Financial Analysts Journal paper argues much of the measured gap is a mechanical artifact of growing fund asset bases rather than mistimed decisions. A behavior gap exists and is persistent; the 15% figure is a stronger claim than the data cleanly supports.

Where is the investor return gap largest?

Consistently in the most volatile categories — sector and thematic funds with dramatic swings — and smallest in broad, diversified allocation funds people buy and hold. That distribution is the strongest evidence that behavior, not just arithmetic, is involved.

How do I avoid the behavior gap?

Automate contributions so they can't be talked out of themselves, favor broad diversified funds if you know you react to volatility, write your rules down before a decline rather than during one, and check your portfolio less often. The gap is created by discretionary decisions made under stress, so removing the decisions removes most of the gap.

Does the behavior gap apply to index fund investors?

Less so, but not zero. Broad index funds show smaller gaps than volatile sector funds, largely because they attract buy-and-hold behavior. An index investor who sells during a crash and rebuys after a recovery still experiences the full effect.

---

Whatever the true average is, yours is your own — and it's measurable. Find out how you behave when it's falling →