Behaviour costs more than fees
The gap between a fund's return and its investors' return is a measurable number — and it is large.
The behaviour gap
A fund can report an 8% annual average while the average investor in it earned noticeably less. The difference does not come from fees — those are already deducted.
It comes from the timing of entries and exits. Money flows in after the good years and out after the bad ones, so most of the capital is there for the falls and missing for the recoveries.
This gap has been measured again and again, and it usually comes out larger than the entire annual fee of an index fund.
Why it happens
A loss hurts roughly twice as much as an equal gain feels good. That is why selling during a fall feels like relief, not like a mistake.
Add to that the tendency to see patterns where there is only noise, and the confidence that grows precisely when prices are high.
None of this goes away just because you know about it. It is kept in check with structure: rules set in advance, while you are calm.
What actually helps
Automatic contributions remove the monthly decision. Rebalancing once a year forces you to sell what rose and buy what fell, without thinking about it at all.
Looking less often helps noticeably. The more often you check your portfolio, the more falls you see, and the stronger the urge to act becomes.
And a written plan — how much risk, why, and what you will do in a 30% fall — is worth more than any market forecast.
Key terms in this lesson
- Behaviour gap
- The difference between a fund's return and the return its investors actually earned.
- Loss aversion
- The tendency to feel a loss roughly twice as strongly as an equal gain.
- Recency bias
- The tendency to assume that whatever happened recently will continue.
Quick check
Why does the average investor earn less than the fund they hold?
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