What Is a Mutual Fund?

If you have ever wondered how people invest without picking individual shares themselves, a mutual fund is usually the answer. Instead of buying one company's shares directly, you buy a small slice of a much bigger pot that a professional manager invests on your behalf, alongside everyone else who has put money in.

In short: a mutual fund pools money from many investors into one fund, run by a manager who buys and sells assets for the whole group. Its price, known as the net asset value, is calculated once a day after the market closes — unlike a share or an ETF, which can be bought and sold throughout the trading day. In the UK you will often see the same basic idea called a unit trust or an OEIC.

Spreading money across many holdings instead of one is also the whole idea behind diversification, and a mutual fund is one of the simplest ways to get that spread without having to research and buy dozens of individual shares yourself.

What exactly is a mutual fund?

A mutual fund collects money from many different investors and combines it into one large pool. A fund manager then uses that pool to buy a basket of assets — shares, bonds, or a mix of both — on behalf of everyone who has put money in.

When you invest in a mutual fund, you are not buying the underlying shares or bonds directly. You are buying units of the fund itself. Each unit represents a small slice of everything the fund owns. If the fund's holdings rise in value, your units rise with them; if the holdings fall, so does the value of your units.

How is a mutual fund priced?

This is the part that trips people up most, because it is genuinely different from how a share works. A mutual fund is priced once per trading day, after the market has closed. The fund adds up the value of everything it owns, subtracts any costs, and divides that total by the number of units in issue. That figure is called the net asset value, or NAV.

Every investor who buys or sells that fund on a given day gets the same NAV price, calculated at the same cut-off point. This matters for a simple reason: there is no point trying to "time" a mutual fund the way some traders try to time a share during the day, because the price you will actually get is only known once, at the end of the day — not at the moment you place your order.

What do UK investors actually call these funds?

If you have come across the terms unit trust or OEIC (open-ended investment company) and wondered how they relate to a mutual fund, the short answer is: they are close cousins. "Mutual fund" is the term used more widely in the US, while unit trusts and OEICs are the UK's legal structures for the same basic idea — a pooled, professionally managed fund, priced once a day.

Many UK and European funds are also labelled UCITS (Undertakings for Collective Investment in Transferable Securities), which is a regulatory standard rather than a different product — it simply means the fund follows a common set of EU investor-protection rules. You do not need to memorise the acronyms; just know that when you see "fund", "unit trust" or "OEIC" on a UK platform, you are looking at the same family of product as a mutual fund.

What are the main types of mutual fund?

• Equity funds invest mainly in company shares, aiming for growth over time.
• Bond funds invest in government or company debt, generally aiming for steadier, more predictable returns.
• Multi-asset funds mix shares, bonds and other assets together in one fund, so you get a ready-made blend rather than building one yourself.
• Money market funds hold very short-term, low-risk instruments and behave more like a place to park cash than a growth investment.

Active vs passive — what's the difference inside a fund?

This split applies across investing generally, but it matters a lot inside mutual funds specifically. An actively managed fund has a human manager (or team) deciding what to buy and sell, trying to beat a benchmark index, in exchange for a higher fee. A passive fund, often called a tracker or index fund, simply aims to mirror a chosen index as closely as possible, with far less decision-making involved — and usually a noticeably lower fee as a result.

Neither approach is automatically "better" for every situation. The honest summary most investors settle on is that active management can occasionally outperform, but doing so consistently, after fees, is hard — which is exactly why passive funds have grown so popular.

How is a mutual fund different from an ETF?

A mutual fund and an ETF (exchange-traded fund) are built on the same core idea — a pooled basket of assets — but they behave differently in practice:

Mutual fund	ETF
Priced once a day, after the market closes	Priced continuously, trades all day like a share
Bought and sold directly through the fund or a platform	Bought and sold on an exchange through a broker
Minimum investment set by the fund provider	You can typically buy as little as one unit

Neither structure is "wrong" — they simply suit different habits. If you want to check a price and trade during the day, an ETF behaves more like a share. If you are comfortable not knowing the exact price until the day's end, a mutual fund works the same way either way.

What does a mutual fund cost?

Running a fund costs money — research, trading, administration — and that cost is passed on to investors as an annual fee, often shown as the ongoing charge figure (OCF) or expense ratio. A platform you buy the fund through may also charge its own separate fee. These numbers look small on paper, often well under 2% a year, but charged every single year, they can quietly take a meaningful bite out of long-term returns. It is one of the first things worth checking before choosing between two similar funds.

What's the catch? Liquidity and risk

Pooling your money with other investors spreads risk across many holdings, but it does not remove risk altogether. The fund still owns real assets, and if those assets fall in value, so does your investment — diversification softens the blow, it does not cancel it out.

There is also a timing quirk worth knowing: if you decide to sell, or "redeem", your units, you do not get a price immediately. You get whatever the NAV turns out to be at the next calculation point, which could be hours away. In calm markets this barely matters. In a fast-falling market, it means you cannot simply exit the instant you decide to — you are committed to whatever price the fund settles on at the end of that day.

How would this fit inside the Challenge?

In the Student Investor Challenge, you build your virtual portfolio by picking individual shares rather than buying a ready-made fund. But the logic behind a mutual fund — spreading money across many holdings instead of betting everything on one — is exactly the same thinking that separates a resilient portfolio from a shaky one in the league tables. Thinking like a fund manager, even while picking your own shares, is a useful habit to build early.

Frequently asked questions

Is a mutual fund the same as an ETF?

No. Both pool money into a shared basket of assets, but a mutual fund is priced once a day after the market closes, while an ETF trades on an exchange all day, with its price moving in real time like an ordinary share.

Can I lose money in a mutual fund?

Yes. A mutual fund still holds real assets such as shares or bonds, so its value can fall if those assets fall. Diversification reduces the damage any single holding can do, but it does not remove market risk altogether.

What's the difference between a unit trust and a mutual fund?

In the UK, "unit trust" and "OEIC" are local names for a structure that works like a mutual fund: a pool of money from many investors, run by a manager, priced once a day. The underlying idea is the same, just wrapped in different legal paperwork.

Do mutual funds pay dividends?

Many do. If the shares or bonds inside a fund pay income, the fund usually passes a share of that on to unit holders, either as a cash payment or reinvested automatically, depending on how the fund is set up. See our dividend explainer for more on how that works.

What's the minimum amount to invest in a mutual fund?

It depends entirely on the provider and platform. Minimums vary a lot, so it is worth checking the details for a specific fund rather than assuming a fixed figure.

Is an index fund the same as a mutual fund?

An index fund is a type of fund, not a separate thing. It can be structured as a mutual fund or an ETF, and what makes it an "index fund" is that it tracks a market index closely, rather than having a manager pick investments.

A mutual fund will not make investing decisions disappear — someone still has to choose a fund, understand its costs, and accept that pooled investing reduces but never removes risk. What it offers is a practical shortcut to the diversification that underpins almost every sensible asset allocation strategy, without having to assemble it holding by holding.