If I’d invested £12.5k in this stock market index 40 years ago, I’d now have £1m

This simple calculation shows that investing in the stock market for the long term is one of the best ways to build lasting wealth.

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.

Storytelling image of a multiethnic senior couple in love - Elderly married couple dating outdoors, love emotions and feelings

Image source: Getty Images

When investing, your capital is at risk. The value of your investments can go down as well as up and you may get back less than you put in.

Read More

The content of this article is provided for information purposes only and is not intended to be, nor does it constitute, any form of personal advice. Investments in a currency other than sterling are exposed to currency exchange risk. Currency exchange rates are constantly changing, which may affect the value of the investment in sterling terms. You could lose money in sterling even if the stock price rises in the currency of origin. Stocks listed on overseas exchanges may be subject to additional dealing and exchange rate charges, and may have other tax implications, and may not provide the same, or any, regulatory protection as in the UK.

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.

When it comes to stock market indexes, most UK investors tend to focus on the FTSE 100. That’s understandable, as the Footsie is the UK’s main index and it contains many well-known companies.

However, there’s an index that has significantly outperformed the FTSE 100 over the long term. If I’d put £12.5k into this index 40 years ago, my investment would now be worth about £1m.

A powerhouse of an index

The one I’m talking about is the S&P 500 – the US’s main stock market index. A powerhouse of an index, it’s home to some of the most dominant companies in the world, including the likes of Apple, Amazon, Tesla, and Nvidia.

It’s quite easy to find historical performance data on the S&P 500. And this can provide some really interesting insights.

Playing around with a historical return calculator last week, I calculated that if I’d invested £12.5k in the index in November 1983, that money would be worth around £1m today when dividends are included (this factors in GBP/USD exchange rates).

The small print

Now, there are a few issues to point out with this calculation. Firstly, £12.5k 40 years ago was a lot more money than it is today. Adjusted for inflation, it’s probably equivalent to around £40k in today’s money.

Secondly, 40 years ago, it probably wasn’t possible to get direct exposure to the S&P 500 index as a UK investor.

Index funds were in existence in the US at the time, however, they weren’t a mainstream investment here in the UK.

Third, the calculation doesn’t factor in taxes, fees, or transaction costs. Finally, 40 years ago, I was only four years old. And a four-year old me wasn’t looking to invest £12.5k.

Still, it’s a pretty amazing calculation, to my mind.

By comparison, a £12.5k investment in the FTSE 100 index when it launched a few months later (in January 1984) would have grown to around £220,000 today.

The power of the stock market

As for the takeaways here, there are several. These calculations show the benefit of diversifying a portfolio internationally. And more specifically, allocating some capital to US stocks.

The US has a long history of innovation and entrepreneurship. This entrepreneurial spirit has led to the creation of some of the world’s most successful companies, which, in turn, has led to huge returns for investors.

Meanwhile, the calculations also show the power of long-term stock market investing. Over the long run, the S&P 500 index has generated a return of around 10% a year.

That doesn’t sound like that much. Yet, over a period of 40 years, 10% a year can turn even a little amount of money into an enormous sum due the power of compounding (earning returns on previous returns).

Lastly, they show that the stock market can be a great vehicle for building wealth for future generations. By investing on behalf of our children when they are young, we can potentially set them up for life.

Should you invest, the value of your investment may rise or fall and your capital is at risk. Before investing, your individual circumstances should be assessed. Consider taking independent financial advice.

Edward Sheldon has positions in Amazon, Apple, and Nvidia. The Motley Fool UK has recommended Amazon, Apple, Nvidia, and Tesla. John Mackey, former CEO of Whole Foods Market, an Amazon subsidiary, is a member of The Motley Fool’s board of directors. 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

Investing Articles

After plunging 65%, is this forgotten FTSE blue-chip the best share for me to buy today?

Harvey Jones is looking for the best share to buy for his Stocks and Shares ISA in 2025 and thinks…

Read more »

Investing Articles

How much do I need to invest in dividend stocks to earn a £1,000 monthly passive income?

Stephen Wright thinks he could turn £15,000 today into £1,000 per month by using one of his favourite dividend stocks…

Read more »

Investing Articles

Down 16% in 2024, will the BP share price bounce back in 2025?

Andrew Mackie assesses why BP remains the laggard among the oil supermajors, and the prospects for its share price this…

Read more »

Investing Articles

As NATO eyes a spending surge in Trump’s second term, is it time for me to buy this FTSE defence technology gem?

This FTSE firm is at the cutting edge of defence technology so looks perfectly placed to benefit from big, planned…

Read more »

Investing Articles

2 no-brainer FTSE 100 value shares to consider buying in 2025

These value shares consistently pop up in UK investor's portfolios. For beginners eyeing long-term growth, they make a compelling case.

Read more »

Arrow symbol glowing amid black arrow symbols on black background.
Investing Articles

Time for me to increase my holding in this 11.1%-yielding FTSE 250 gem to target £45,811 in annual passive income?

This FTSE 250 firm offers one of the highest yields in any major FTSE index, which could one day generate…

Read more »

Satellite on planet background
Investing Articles

As the S&P 500 falls back below 6,000, what does 2025 hold for this infamous US tech stock?

Analysts have mixed forecasts for the S&P 500 as Trump's trade tariffs dominate news. But our writer remains bullish about…

Read more »

Smiling white woman holding iPhone with Airpods in ear
Investing Articles

1 New Year’s resolution for ISA investors

With the US stock market getting a little hot and with limited momentum among UK-listed stocks, our Foolish writer highlights…

Read more »