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Does a bigger mutual fund perform better? We split the list and checked

By ReturnKoto? | Published 25 August 2026 | Updated 24 September 2026

Large funds carry an air of safety. We split every tracked fund at the median size and compared the two halves over the same window.

These figures update themselves. Every number below is recalculated from NAV history each day, so this page is current as of 24 September 2026 rather than the day it was written.

Fund size gets used as a proxy for quality. A larger fund feels established, and the reasoning is rarely examined beyond that feeling.

Size is published, and so is return, so the claim is testable.

Splitting the list at the median

We sorted every tracked fund by assets under management, cut the list in half, and averaged the annualised return of each half over 2 years.

The larger half averaged 11.39% a year. The smaller half averaged 7.52%.

The gap between the two halves came to 3.86 percentage points, with larger funds ahead.

UCB Income Plus Fund is the largest fund tracked.

If size decided returns, the dots would climb from left to right. Look for that slope before reading the averages.

Why this test proves less than it appears to

A median split across 35 funds over one window is a weak instrument, and it would be dishonest to present the result as a finding about fund size in general.

Fund type is tangled up in it. If income funds happen to be larger on average, and income funds happened to do well over this window, the split will show large funds winning for a reason that has nothing to do with size.

So here is the same split run inside each type, where every fund is compared only with funds doing the same job.

Age is tangled up in it too. Bigger funds are usually older funds, so a size comparison is partly an age comparison.

Splitting the same funds by how long their record runs instead: the half with the longest records averaged 9.40% a year, the half with the shortest 9.40%, a gap of 0.00 points with the shorter records ahead.

The honest conclusion is narrower than the headline: over this window, in this market, the difference between the halves was 3.86 percentage points, while the best and weakest individual funds were 19.66 points a year apart.

What size does genuinely affect

Two things, neither of which shows up cleanly in a return figure.

A large fund moves more slowly. Buying or selling a meaningful position in a smaller listed company takes longer and moves the price against it, which limits where a big fund can go. A smaller fund can hold positions that would be impractical at scale.

A very small fund carries a different problem. Fixed running costs are spread across fewer taka, so the same expense ratio buys less. It is also more exposed to a single large investor leaving.

Neither effect is visible in a headline return, and neither is a reason to pick on size alone.

A better use for the size figure

Read it alongside the holdings panel rather than on its own. A large fund holding a concentrated set of names is taking a different kind of risk from a large fund spread widely, and the size number alone will not tell them apart.

Every fund page on this site shows assets under management next to the actual portfolio, which is the comparison worth making. Figures through 24 September 2026.

Further reading on this site

• FAQ: what is AUM, or fund size?
• Growth, balanced or income: which kind of fund did what
• Methodology: how returns are calculated

Run these numbers on your own amount