What Are Money Market Funds and Who Should Invest in Them?
According to various sources (here, for example) money market funds or MMFs are seeing a surge of interest from UK investors at the moment.
So today I thought I’d explain what MMFs are, their pros and cons, and who should (and perhaps shouldn’t) invest in them. I will also examine some likely reasons for the high level of interest in MMFs just now.
Let’s start with the most basic question, though…
What Are Money Market Funds?
A money market fund is a type of investment fund that invests in short-term, high-quality, liquid debt instruments — such as government treasury bills, bank certificates of deposit, commercial paper and other instruments with very short maturities. In the UK context, many asset managers describe them as a “park your cash” vehicle: not quite a deposit account, but relatively low risk compared to equities or longer-dated bonds.
Because the underlying assets mature quickly (many in weeks or a few months) the fund manager can reasonably anticipate the yield and maintain high liquidity.
In simple terms, you could think of a money market fund as somewhere between “keeping money in a bank account” and “investing for growth in the stock market” — it aims for capital preservation + modest income, rather than big capital gains.
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Pros of money market funds
If you’re considering an MMF, here are some of the advantages that frequently show up in analyses:
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Lower risk (relatively)
Because the underlying holdings are short-dated and usually high credit quality, money market funds tend to carry lower risk than many other types of investment funds. For example, compared to longer-term bond funds or equities, there’s far less exposure to interest-rate/inflation risk and less time for issuers to go horribly wrong. -
High liquidity
Many funds allow you to redeem on a daily dealing basis (or very frequently) so you can access your money relatively quickly. This makes them useful as a “waiting place” for money or for short-term needs. -
Potentially higher return than pure cash savings
Especially in a higher interest-rate environment, the yields on money market funds can exceed those of some bank savings accounts or easy-access deposits — for investors willing to accept the (small) additional risk. -
Diversification of cash holdings
If you keep large sums of cash at one bank, you may be exposed to that institution; a money market fund spreads the credit risk across many issuers. -
Use within tax-efficient wrappers
In the UK, you can hold money market funds inside a Stocks and Shares ISA or SIPP, which may be advantageous rather than leaving all your money in a conventional cash account.
Cons of money market funds
As always, “lower-risk” doesn’t mean “no risk”, and there are some important drawbacks to bear in mind…
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Capital is not guaranteed
Unlike deposit accounts covered by the UK’s Financial Services Compensation Scheme (FSCS) (up to £85,000 per institution), investments in money market funds are subject to investment risk. You could get back less than you invested. -
Return may not beat inflation
Because the returns are modest (given the conservative nature of the underlying assets), there is a risk that inflation will erode the real value of your money over time. In other words: you may earn income, but your purchasing power may still decline. -
Interest-rate/yield sensitivity
The yield of a money market fund is influenced by short-term interest rates. If interest rates fall, the yield on the fund may drop. If the market is unsettled (or credit spreads widen) the value can move. -
Liquidity risk in extreme scenarios
While these funds are normally very liquid, in times of market stress there is still a risk of redemption delays, or assets becoming harder to value. Some regulators have highlighted this as a risk. -
Limited capital growth potential
These funds are designed for preservation and modest income, not high growth. If your goal is expanding your wealth significantly over many years, other assets (equities, long-term bonds, etc.) may suit you better.
Who Should Invest in MMFs?
Here are some scenarios where a money market fund may be a good fit:
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If you have short-term needs (e.g. you expect to spend the money within the next 1 to 3 years) and want to avoid exposing it to the ups and downs of equities.
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If you’re deciding what to do with funds (e.g. waiting for an investment opportunity) and need a place to park cash that offers a little bit more than a basic savings account, while keeping reasonable access.
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If you hold a large sum of cash in an ISA or pension wrapper and you want it to “work a little harder” than a pure deposit, but without taking large risks.
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If you have low risk-tolerance and want the bulk of your capital in safer, more liquid form — while still preserving flexibility.
Who Shouldn’t Invest In MMFs (or maybe think twice)?
On the flip side, money market funds may not be appropriate if:
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Your investment horizon is long-term (say 5-10+ years) and you’re seeking substantial growth. The conservative nature of money market funds means they are unlikely to match the returns of equity or balanced portfolios over the long term.
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You are relying on the investment to outpace inflation significantly. If inflation is high, the modest returns may mean your real-terms wealth declines.
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You need instant access or expect frequent withdrawals. While liquidity is good relative to many investments, it is not always instant and sometimes there may be daily dealing only. Check the individual fund terms.
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You misunderstand the risk: if you assume it’s the same as a deposit account (with full guarantee), you may be unpleasantly surprised. While risk is lower than many funds, it is not zero.
Examples of Popular UK MMFs
To illustrate what’s out there in the UK market, here are a few examples of well-known money market (or “cash/money-market”) funds. Note: this is for information only and not a product recommendation.
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Royal London Short Term Money Market Fund — This fund is often cited as a top choice in the UK short-term money market fund category, with a low ongoing charge and yield of ~4–5% in recent years.
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Vanguard Sterling Short‑Term Money Market Fund — Vanguard’s UK money market offering, described as “a low-risk place to park your money” by the provider.
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abrdn Sterling Money Market Fund — Another UK-available fund in the segment, targeting short-term money market instruments and relatively modest returns.
When choosing a fund, you’ll want to consider: the fund’s objective, charges (ongoing management charge/OCF), dealing terms (how quickly you can withdraw), liquidity provisions, and whether the yield is appropriate for the risk.
Why Is Interest in MMFs High Right Now?
There are various reasons for this. A major one is a degree of caution among investors at present. Equities and long-duration bonds have had episodes of volatility, inflation remains a concern, and with rising rates the risk of capital losses in interest-sensitive assets is higher. In that context, MMFs — with their short-duration holdings and relatively low volatility — look like a safer option to hold cash or near-cash assets.
Also, with central banks (including the Bank of England) keeping base rates elevated, the returns available from short-term debt and cash-like instruments have increased. For example, one provider (Fidelity) notes that MMFs “made a comeback in 2023 and have remained popular ever since — thanks largely to interest rates remaining higher for longer than expected.”
Because MMFs can be held inside ISAs or pensions, they benefit from the same tax-efficient wrappers as other investment funds. For investors who already use their ISA or SIPP allowance, being able to park cash inside that wrapper via an MMF may be an attractive alternative to leaving it outside the wrapper in a separate (perhaps taxed) savings account.
And finally, many investors have cash allocations in their portfolios (for future investment or awaiting opportunity) or hold money inside tax-efficient wrappers as mentioned above, but may not want to leave it entirely in a low-interest bank account. MMFs provide a way to hold cash within an investment platform, maintain liquidity, and potentially earn slightly more than a basic savings account. For example, AJ Bell notes that one of the appeals is that an investor can hold the MMF inside their S&S ISA or pension without transferring it out to a separate cash savings account.
- UPDATE: An additional attraction of MMFs has arisen due to the decision by Chancellor Rachel Reeves in her November 2025 Budget to reduce the annual Cash ISA allowance to £12,000 (with an exception for over-65s). If you would previously have put the full £20,000 into a Cash ISA, you could now put all that money into an MMF within a Stocks and Shares ISA instead. Alternatively you could put the maximum £12,000 into a Cash ISA and the remaining £8,000 into a MMF within a S&S ISA.
Key Takeaways
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Money market funds can be a useful tool for parking money (relatively) safely, earning a bit more than a basic savings account, and maintaining liquidity.
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They are not risk-free: capital is at risk, and returns may not keep pace with inflation.
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They are most useful for short- to medium-term horizons, or as part of a diversified portfolio where some portion of assets is kept in safer, liquid form.
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If you’re investing for the long term with a view to growth, you’ll likely need to supplement (or allocate differently) rather than relying solely on MMFs.
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You can invest in MMFs directly or via a platform such as AJ Bell or Hargreaves Lansdown.
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You can invest within a tax-free wrapper such as a SIPP or S&S ISA, or in a general investment account without tax-free status if you’ve used up your annual £20,000 ISA allowance.
- Always read the fund’s Key Investor Information Document (KIID) or factsheet, check charges, underlying holdings and suitability for your goals and time horizon.
Comparison Chart: MMFs vs Bank Deposits vs Cash ISAs
| Product type | Typical recent yield / rate* | Key features / caveats |
|---|---|---|
| Money Market Funds (UK) | Around ~3.9%-4.3% p.a. (e.g. Premier Miton UK Money Market Class B shows an underlying yield ~3.98%. | Variable yield; invested in short-dated instruments; not guaranteed like a deposit; liquidity good but subject to fund terms. May be held within a tax-free wrapper such as a SIPP or ISA. |
| UK bank deposits / savings accounts | For easy‐access/variable savings: up to ~4.20% or so. | Usually FSCS-protected up to £85,000; rates may change; access may be immediate or with notice depending on account. |
| Cash ISAs (UK) | Top easy‐access Cash ISAs: ~4.52% AER or thereabouts. | Tax-free interest; also FSCS-protected as with deposits; you must use your annual ISA allowance (£20,000 in 2025/26) for it to count as an ISA; yield may be variable or fixed term. |
*Yields/interest shown are approximate at the time of writing and subject to change.
As the chart shows, if you’re looking for a place to “park” money in the UK, you’re getting broadly similar yields whether you go for a bank savings account, a cash ISA or a money market fund. The differences come down to tax treatment, level of guarantee/risk, which wrapper you use, and ease of access.
For example, a cash ISA is tax-free, which can boost your effective return if you’re a higher rate taxpayer. A bank deposit may offer the FSCS safety net. A money market fund may allow you to invest via your ISA or pension wrapper and keep your cash within your investment portfolio structure, but you must accept that capital preservation isn’t guaranteed.
If you value the FSCS protection and are comfortable with a savings account structure, a bank deposit or savings account/cash ISA might be your preference. If you already have your deposit needs covered and you’re simply looking for a place inside your investment wrapper to hold cash-like assets, a money market fund may fit the bill.
It’s also important to ascertain whether the quoted rate is fixed or variable, check any withdrawal penalties, and consider whether the returns will keep pace with inflation.
As always, if you have any comments or questions about this post, please do leave them below. Bear in mind that I am not a qualified financial adviser and nothing in this article should be construed as personal financial advice. You should always do your own ‘due diligence’ before investing and seek professional advice if in any doubt how best to proceed. All investing carries a risk of loss.