How to Start Investing in Index Funds UK
TLDR
- Index funds track a market index like the FTSE 100 or MSCI World, giving you exposure to hundreds or thousands of companies in a single purchase.
- A global index fund inside a Stocks and Shares ISA is the simplest and most tax-efficient way to start building wealth in the UK.
- The cheapest global index funds charge as little as 0.07% per year. Over 30 years, the difference between a cheap and expensive fund can be six figures.
- You can start with as little as a few pounds a month. The habit of regular investing matters far more than the starting amount.
How to Start Investing in Index Funds UK
How to start investing in index funds in the UK is one of the most common questions new investors ask, and the answer is more straightforward than you might expect. You do not need a financial adviser, a large lump sum, or any special knowledge. You need a platform, a tax-free account, and one well-chosen fund.
This guide covers exactly what index funds are, which ones to buy, and how to set everything up.
Contents
- What is an index fund?
- Why index funds beat most alternatives
- Which index fund should you buy?
- Index fund vs ETF: what is the difference?
- How to buy your first index fund
- Frequently Asked Questions
What is an index fund?
An index fund is an investment fund that tracks a market index. Instead of a fund manager picking stocks they think will do well, the fund simply holds every stock in the index, in proportion to its size.
The FTSE 100 index contains the 100 largest companies listed on the London Stock Exchange. A FTSE 100 index fund owns all 100 of them. If Shell makes up 8% of the index, the fund holds 8% in Shell. If AstraZeneca makes up 6%, the fund holds 6% in AstraZeneca. The fund mirrors the index mechanically - no human judgment involved.
This extends to global indices. The FTSE All-World index tracks over 4,000 companies across 49 countries. Buy a fund that tracks it and you own a slice of virtually every publicly traded large and mid-cap company on the planet. Apple, HSBC, Toyota, Nestle - all of them.
The term tracker fund means the same thing. So does passive fund. They all describe a fund that follows a rules-based index rather than relying on a manager's stock-picking ability. If you want to understand the philosophy behind this approach, our guide to passive investing in the UK covers the evidence in detail.
Why index funds beat most alternatives
Index funds are not exciting. They will never double in a year. You will never brag about owning one at a dinner party. But they beat the vast majority of professionally managed funds over any meaningful time period.
The S&P SPIVA Europe Scorecard shows that over 10 years, more than 80% of actively managed UK equity funds fail to beat their benchmark index after fees. The longer the time period, the worse the numbers get for active managers.
The main reason is cost. An active fund typically charges 0.75-1.50% per year for a team of analysts to pick stocks. An index fund charges 0.07-0.25% because it just follows the rules of the index. That fee gap compounds brutally over decades.
On a £30,000 portfolio growing at 7% per year for 25 years, the difference between paying 0.15% and 1.00% in annual fees is roughly £45,000. That is not a theoretical number. That is money that either compounds in your pocket or gets paid to a fund manager who probably underperforms the index anyway.
Which index fund should you buy?
For most UK investors starting out, a global tracker is the right first fund. It holds thousands of companies across every major economy, giving you maximum diversification in a single purchase. You do not need to decide how much to put in the US vs Europe vs emerging markets - the fund handles it for you, weighted by market capitalisation.
The best global index funds for UK investors
| Fund | Type | Index tracked | OCF |
|---|---|---|---|
| Amundi Prime All Country World ETF (PACW) | ETF | Solactive GBS Global Markets Large & Mid Cap | 0.07% |
| HSBC FTSE All-World Index Fund | OEIC | FTSE All-World | 0.13% |
| Vanguard FTSE All-World ETF (VWRP) | ETF | FTSE All-World | 0.22% |
| Vanguard FTSE Global All Cap Index Fund | OEIC | FTSE Global All Cap | 0.23% |
The OCF (Ongoing Charges Figure) is the annual fee. Lower is better, but it is not the only consideration. Total Cost of Ownership includes trading costs and tracking error - the gap between the fund's return and the index's return. For a deeper dive on comparing fund costs properly, see our guide on choosing a low-cost index fund.
Do you need more than one fund?
No. A single global tracker is a complete portfolio. Jack Bogle, the founder of Vanguard and the person who invented the index fund, was a lifelong advocate of keeping it simple. His Bogleheads philosophy still guides millions of investors today. One fund, regular contributions, decades of patience.
Some investors later add a UK bond fund for stability as they approach retirement, or a small UK equity tilt for higher dividends. But these are refinements, not requirements. Do not let the desire for a "perfect" portfolio stop you from starting with a good one.
Index fund vs ETF: what is the difference?
You will see both "index funds" and "ETFs" recommended. Both track an index. The difference is how you buy them.
An index fund (technically an OEIC or unit trust in the UK) is bought directly from the fund provider. You place an order and it gets filled at the next valuation point, usually once a day. You can set up automatic monthly investments easily.
An ETF (exchange-traded fund) is listed on a stock exchange, like a share. It trades throughout the day at whatever price buyers and sellers agree on. ETFs can be slightly cheaper than equivalent index funds, and some platforms (like InvestEngine) specialise in them.
| Feature | Index fund (OEIC) | ETF |
|---|---|---|
| Pricing | Once daily | Real-time during market hours |
| Auto-invest | Easy to set up | Depends on platform |
| Minimum investment | Often £100-£500 | Usually one share (£5-£80) |
| Costs | Sometimes slightly higher | Sometimes slightly lower |
For long-term investors, the choice makes little practical difference. Pick whichever your platform supports best. If you are on Vanguard Investor, you will mostly use OEICs. If you are on InvestEngine, you will use ETFs.
How to buy your first index fund
Here is the practical walkthrough:
1. Choose a platform
For most beginners, Trading 212 is the best place to start. It charges zero platform fees and zero commission on ETFs, with no minimum investment. InvestEngine is another strong free option for ETFs. Vanguard Investor charges 0.15% (capped at £375/year) but limits you to Vanguard funds only.
2. Open a Stocks and Shares ISA
Every platform will walk you through this during signup. You need your National Insurance number, a form of ID, and about 10 minutes. The ISA is tax-free - no capital gains tax or dividend tax on anything inside it.
3. Fund your account
Transfer money in via bank transfer or direct debit. Some platforms accept debit cards. There is no wrong way to do this.
4. Search for your chosen fund
On Vanguard, search "Global All Cap". On InvestEngine, search "VWRP" or "PACW". The platform will show the fund's factsheet with its performance history, holdings, and costs. If you are not sure what to look for, our guide on how to read an ETF factsheet breaks it down.
5. Buy
Enter the amount you want to invest and confirm. For OEICs, the order fills at the next valuation point. For ETFs, it fills immediately during market hours.
6. Set up a regular investment
This is the most important step. Set up an automatic monthly contribution so your investing happens on autopilot. Pay yourself first, before the money can be spent on anything else.
That is it. You are now an index fund investor.
Frequently Asked Questions
Are index funds safe?
No stock market investment is "safe" in the short term. A global index fund can fall 20-40% during a crash. But over periods of 10 years or more, diversified global index funds have historically always recovered and grown. The risk of holding cash long-term (inflation eroding your purchasing power) is arguably greater than the risk of holding a diversified index fund.
How much money do I need to start investing in index funds?
Some platforms let you start with £1. Vanguard requires £500 as a lump sum or £100 per month. InvestEngine and Trading 212 have no minimum. The amount is far less important than starting the habit.
Can I lose money in index funds?
Yes, in the short term. Markets fall regularly. A global index fund lost about 34% during the 2020 Covid crash and about 25% during the 2022 downturn. But both times, it recovered within months to a couple of years. If you are investing for 5+ years and can tolerate short-term drops, index funds have been the most reliable long-term wealth builder available.
What is the best index fund in the UK?
There is no single "best" because it depends on your platform and preferences. For pure cost, the Amundi Prime All Country World ETF (PACW) at 0.07% is the cheapest global option. For simplicity on Vanguard's platform, the FTSE Global All Cap Index Fund is the default choice. For a well-known, highly liquid ETF, the Vanguard FTSE All-World (VWRP) is popular. All three track essentially the same thing - global equities.
Should I invest in a FTSE 100 index fund?
A FTSE 100 fund gives you exposure only to the 100 largest UK companies. That is about 4% of the global stock market. A global tracker gives you the FTSE 100 plus thousands of other companies worldwide. For most investors, a global fund is the better starting point because it is far more diversified. You can always add a dedicated UK fund later if you want higher dividend income or reduced currency risk.
Further Reading
The Little Book of Common Sense Investing - John Bogle - The original case for index fund investing, written by the man who created Vanguard and the first index fund available to ordinary investors. (Affiliate link - we may earn a small commission at no extra cost to you.)
Smarter Investing - Tim Hale - The UK-specific guide to building a low-cost, evidence-based portfolio, with practical advice on asset allocation, fund selection, and tax wrappers. (Affiliate link - we may earn a small commission at no extra cost to you.)
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