Strategy

The Behavior Gap: Why Investors Trail Their Own Funds

Funds and their investors report different returns for the same decade. Work an example where the fund gains and the investor loses, then read what the studies measured.

By the Euphoria team · 2026-07-31 · 8 min read

Two honest answers to the same question

Ask a fund how it did over the last decade and it will quote a total return. Ask the people who owned it and, on average, they will report something lower. Both answers are correct, neither is a marketing trick, and the distance between them has been measured repeatedly for nearly twenty years.

The reason is that the two numbers answer different questions. A fund's published return assumes you invested a lump sum on day one and never touched it. Almost nobody invests that way. Money goes in from paychecks, sometimes on a fixed schedule, comes out for a car, goes in again after a good year, comes out after a bad month. Once the amount invested changes over time, the return your dollars earned depends on when they were there, and that is a different calculation from the one on the fact sheet.

• 7.3% the average annual total return of US funds over the decade to 2023
• 6.3% what the average dollar invested in them actually earned
• 1.1 points the gap, roughly 15 percent of the total return

The two measurements, defined

Time-weighted return measures the investment. It chops the period into segments at every cash flow and links the segments together, which strips out the effect of money moving in and out. That is deliberate: it is designed to judge a manager, who does not control when you deposit. Every total return you see quoted on a fund is this one.

Dollar-weighted return, also called money-weighted return or internal rate of return, measures the investor. It is the single annual rate that, applied to your actual deposits and withdrawals on the actual dates, produces your actual ending balance. It is the return your money earned, and it is the only one that corresponds to whether you have more or less than you put in.

Subtract one from the other and what remains is timing. That residual is the behavior gap.

A case where the fund wins and the investor loses

Arithmetic makes this concrete faster than any argument.

A fund returns positive 25 percent in its first year, negative 30 percent in its second, and positive 20 percent in its third. Multiply those together and a lump sum held throughout would have grown 5 percent over the three years, about 1.6 percent a year. Modest, but positive.

Now put an investor in it. She starts with $1,000. After the 25 percent year she has $1,250, feels good about it, and adds $5,000 at the start of year two. The 30 percent decline takes the $6,250 balance down to $4,375. She adds nothing in year three, and the 20 percent recovery brings her to $5,250.

She contributed $6,000 in total and finished with $5,250. She is down $750, a dollar-weighted return of about negative 6 percent a year, in a fund that gained 5 percent over the same three years.

Nothing was hidden from her. The fund reported its results honestly. Her large contribution simply arrived just before the worst of the three years, so most of her money experienced only the decline and the partial recovery, while the initial $1,000 was the only dollar present for the good year.

What has actually been measured

The most citable work on this is Morningstar's Mind the Gap study, published annually. The 2024 installment, covering the ten years ended December 31, 2023, found that fund investors earned a dollar-weighted return of 6.3 percent a year while the funds themselves returned about 7.3 percent. The 1.1 percentage point annual shortfall works out to roughly 15 percent of the total return the funds produced.

The method matters, so here it is. Morningstar estimates the return of the average dollar invested, using the money flowing into and out of each fund month by month, then compares that with the fund's reported total return. It is an estimate of a population, calculated from aggregate flows. It is not a survey of individual brokerage statements, and it does not say that a given investor lost 1.1 points.

The gap was not uniform.

Allocation funds, the all in one funds that hold a fixed blend of stocks and bonds and rebalance themselves, had the narrowest gap at negative 0.4 percentage points a year. Index funds came in at negative 0.8 and active funds at negative 1.2. The extreme was in the most volatile sector equity funds, where the average dollar trailed the buy and hold return by more than 7 percentage points a year. Morningstar also reported that the gap was negative in all ten calendar years of the study period, and that it was widest in 2020.

That pattern is the most informative part of the study. The gap tracks how much a fund moves and how easy it is to transact in. Funds that live inside retirement plans and rebalance on autopilot produced small gaps. Funds that invite a decision produced large ones.

Three mechanisms, named properly

The finding is a measurement. The explanations are a separate question, and they come from experimental psychology rather than from fund data.

Loss aversion is the finding that a loss of a given size registers as more painful than an equivalent gain feels good, by roughly a factor of two in laboratory settings. The consequence is not that people hate risk. It is that a decline creates pressure to act which an identical rise does not, and acting during a decline is what converts a paper loss into a realized one.

Recency is the tendency to weight the most recent stretch of experience far more heavily than a longer record when estimating what happens next. Three good quarters feel like evidence about the future. Statistically they are mostly noise. Recency is what makes a fund most attractive precisely after it has already gone up, which is also when new money tends to arrive.

The third has no standard name, so call it the diligence illusion. In nearly every other part of life, paying closer attention and adjusting more often produces better results. Studying more raises a grade. Checking a recipe improves dinner. Investing is one of the few domains where the same effort can subtract value, because each adjustment is a new opportunity to be wrong and often carries a cost. The work feels identical to useful work. That is exactly what makes it hard to notice.

How solid is any of this

This is where a lot of writing on the subject overreaches, so a few honest boundaries.

Studies of this gap differ in method and produce very different magnitudes. Some of the largest published figures come from studies that compare aggregate industry flows against index returns rather than against the funds actually held, a method that has been criticized for attributing to behavior effects that belong to the composition of what people owned. Several widely quoted estimates are published by firms that sell services to financial advisers, for whom a large gap is a useful sales argument. Morningstar is itself a commercial data provider. None of that makes a study wrong, but it does mean the size of the gap is contested in a way the existence of the gap is not.

There is also a mechanical component that has nothing to do with mistakes. Because balances grow over time, the average dollar in almost any fund is present for the later part of a period rather than the earlier part. If a fund's strongest years came early, the dollar-weighted return will be lower than the total return even if every investor behaved with perfect discipline. Part of the measured gap is sequence, not judgment, and no study can fully separate the two.

What survives all of that is the direction. Across methods, periods, and providers, the return earned by the money has been lower than the return earned by the funds. That is a robust finding. The precise toll is not.

What changes once you can see it

The practical value here is not a rule. It is a second number.

Most brokerage apps display the return of your holdings, which is the time-weighted figure, because that is what the fund reports. Some also show a personal rate of return, which is usually the dollar-weighted one. When those two numbers differ, the difference is not an error in the app. It is your own timing, measured, and it is the only version of the number that reflects what happened to your money.

Knowing which one you are looking at also changes how you read a claim in the wild. A fund advertising a ten year return is telling you what the strategy did. It is not telling you what its investors got, and those have been two different figures for as long as anyone has bothered to check.

Euphoria is built so this distinction shows up while it is still cheap to learn. Paper trading records every entry and exit with a date on it, so the app can show you your holdings' return next to your own, and the gap between them becomes a fact about you rather than a study about somebody else.