What are FTSE 100 index funds and could they help me towards early retirement?

Index trackers are not overly complicated instruments, as Jonathan Smith explains.

The content of this article was relevant at the time of publishing. Circumstances change continuously and caution should therefore be exercised when relying upon any content contained within this article.

You’re reading a free article with opinions that may differ from The Motley Fool’s Premium Investing Services. Become a Motley Fool member today to get instant access to our top analyst recommendations, in-depth research, investing resources, and more. Learn More.

Do you think stock market investing is all about spending lots of time reading up on stocks, analysing technical indicators and keeping abreast of market-moving events? And is that putting you off taking your first step?  If so, an index fund (also known as an index tracker) could be a great idea for your portfolio. Indeed, it can even contribute towards early retirement.

What are index funds?

Simply put, an index fund is a financial product you can buy that mimics the performance of a financial index (the clue’s in the name!) This is sometimes why index funds are known as trackers. It wouldn’t make sense for someone to mimic the performance of one stock — these funds copy the performance of a group of stocks such as the well-known stock market indices.

For the purpose of this article, I will be focusing on a FTSE 100 index fund. Yet it is useful to know that an index fund in theory can track a vast variety of different groups of stocks. It could echo the NASDAQ index in America, or the healthcare sector in Japan, for instance. 

What is the point of an index fund?

An index fund allows you to track the performance of something that otherwise would be hard for you to replicate yourself. The FTSE 100, logically, has 100 firms within it at any point in time. It would take you an awfully long time (and a lot of cash) to buy 100 separate stocks. Instead, you can simply buy one index tracker based on the FTSE 100 and track the performance of the 100 firms.

I should note that the index fund will have some margin of error that you need to take into account. This is known as the tracking error and arises for various reasons (most beyond the scope of this article). Sometimes the funds don’t actually own the 100 stocks themselves but the fund managers use financial derivatives to gain exposure to companies. Regardless of that, an index fund is a reliable, affordable, one stop shop for an investor looking to gain access to the index performance.

How can they help me to retire early?

Index funds sum up the ‘buy-and-hold’ philosophy we have at the Motley Fool. They’re designed to offer steady returns and therefore to be held for a long time. They may rise or fall, but over time, the performance is smoothed out and historically speaking, has been positive. 

Secondly, they’re cheaper than buying and selling all the individual stock names yourself. They also save you the time of researching all the companies within the index, allowing you to spend your time earning money from pursuing other income opportunities.

And if you reinvest your dividends in the fund, you can benefit from compounding as your interest earns interest and help you towards your retirement goals.

For newcomers, FTSE 100 index funds may seem like complex products, but instead they’re actually rather simple tools enabling you to potentially grow your wealth.

Jonathan Smith and The Motley Fool UK has no position in any of the shares mentioned. Views expressed on the companies mentioned in this article are those of the writer and therefore may differ from the official recommendations we make in our subscription services such as Share Advisor, Hidden Winners and Pro. Here at The Motley Fool we believe that considering a diverse range of insights makes us better investors.

More on Investing Articles

Man writing 'now' having crossed out 'later', 'tomorrow' and 'next week'
Investing Articles

The best time to buy stocks? It might be right now

Short-term issues that delay long-term trends create opportunities to buy stocks. And that could be happening right now with a…

Read more »

Queen Street, one of Cardiff's main shopping streets, busy with Saturday shoppers.
Investing Articles

Here’s why Next stock rose 5% and topped the FTSE 100 today

Next was the leading FTSE 100 stock today, rising 5%. Our writer takes a look at why and asks if…

Read more »

Renewable energies concept collage
Investing Articles

Up 458% in a year, could the Ceres Power share price go even higher?

Christopher Ruane reviews some highs and lows of the Ceres Power share price over the years and wonders whether the…

Read more »

Rolls-Royce's Pearl 10X engine series
Investing Articles

Are the glory days over for Rolls-Royce shares?

Rolls-Royce shares have soared in recent years. Lately, though, they have taken a tumble. Could there be worse still to…

Read more »

Group of friends meet up in a pub
Investing Articles

Are ‘66% off’ Diageo shares a once-in-a-decade opportunity?

Diageo shares have taken another hit in the early weeks of 2026. Are we looking at a massive bargain or…

Read more »

Investing Articles

Meet the UK stock under £1.50 smashing Rolls-Royce shares over the past year

While Rolls-Royce shares get all the attention, this under-the-radar trust has quietly made investors a fortune. But is it still…

Read more »

UK financial background: share prices and stock graph overlaid on an image of the Union Jack
Investing Articles

Down 19%, the red lights are flashing for Barclays shares!

Barclays shares have fallen almost a fifth in value as the Middle East war has intensified. Royston Wild argues that…

Read more »

Aviva logo on glass meeting room door
Investing Articles

After falling another 5%, are Aviva shares too cheap to ignore?

£10,000 invested in Aviva shares five years ago would have grown 50% by now. But what might the future hold,…

Read more »