Here’s how I’d invest a £20,000 Stocks and Shares ISA to help build long-term wealth

This writer thinks a £20K Stocks and Shares ISA could be turned into something much, much bigger over time. Here’s how he’d try to make that happen.

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.

Older couple walking in park

Image source: Getty Images

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.

A Stocks and Shares ISA with £20,000 in it could give me a welcome opportunity to invest in a range of great companies.

But might it realistically let me try and build wealth over the long term? I think the answer to that is ‘yes’.

Why a long-term approach matters

When I talked about building wealth, I was not focusing on this month, this year, or even necessarily this decade.

Instead I would treat my Stocks and Shares ISA with a long-term perspective. To understand why that is important, consider an analogy used by billionaire investor Warren Buffett. He compares investing to a snowball. As it moves downhill, it picks up more snow that, in turn, can pick up even more. So the snowball’s rate of growth increases over time.

The same applies to an ISA. Imagine that you achieve a compound annual growth rate of 5% on a £20,000 ISA. After 10 years, it would be worth around £31,000. After 20 years, it would be worth over £50,000.

But after 30 years, the valuation would be over £82,000. Each decade brings bigger returns even at the same growth rate. That is the snowball effect.

Risk and reward

With a long-term approach, I would not just focus on potential reward. Longer timeframes mean there is more time for risks to materialise too.

Buffett says that the first rule of investing is never to lose money and the second rule is never to forget the first one.

In other words, smart and consistently successful investors do not just look at the potential for a share to soar. They also always seriously consider the potential risks involved.

Growth and income

What would be better for my Stocks and Shares ISA in the long run? Buying into high-yield shares like Legal & General and Phoenix, or owning shares with the potential for the sort of explosive growth seen over the decades at firms like Amazon and Google parent Alphabet?

That is a difficult question and I am not sure there is necessarily only one right answer.

Owning the right Income shares could help me compound my earnings over time. But getting into a massive growth story at the right price might provide enormous returns.

One issue with growth shares is that, for every Amazon or Alphabet, there are lots of other companies that do not perform anywhere near as well. It seems obvious now that buying into Amazon 20 years ago would have been an investing masterstroke. But that was not necessarily anything like so obvious back then.

So I would be happy splitting my £20,000 between both growth and income shares.

In each case my focus would be on trying to maximise my potential long-term reward while keeping risks at a comfortable level. I would likely spread the £20K across five to 10 shares, to keep my portfolio diversified.

John Mackey, former CEO of Whole Foods Market, an Amazon subsidiary, is a member of The Motley Fool’s board of directors. Suzanne Frey, an executive at Alphabet, is a member of The Motley Fool’s board of directors. C Ruane has positions in Legal & General Group Plc. The Motley Fool UK has recommended Alphabet and Amazon. 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

Will the S&P 500 crash in 2026?

The S&P 500 delivered impressive gains in 2025, but valuations are now running high. Are US stocks stretched to breaking…

Read more »

Teenage boy is walking back from the shop with his grandparent. He is carrying the shopping bag and they are linking arms.
Investing Articles

How much do you need in a SIPP to generate a brilliant second income of £2,000 a month?

Harvey Jones crunches the numbers to show how investors can generate a high and rising passive income from a portfolio…

Read more »

Investing Articles

Will Lloyds shares rise 76% again in 2026?

What needs to go right for Lloyds shares to post another 76% rise? Our Foolish author dives into what might…

Read more »

Investing Articles

How much passive income will I get from investing £10,000 in an ISA for 10 years?

Harvey Jones shows how he plans to boost the amount of passive income he gets when he retires, from FTSE…

Read more »

Investing Articles

Down 34% in 2025 — but could this be one of the UK’s top growth stocks for 2026?

With clarity over research funding on the horizon, could Judges Scientific be one of the UK’s best growth stocks to…

Read more »

piggy bank, searching with binoculars
Investing Articles

Can the rampant Barclays share price beat Lloyds in 2026?

Harvey Jones says the Barclays share price was neck and neck with Lloyds over the last year, and checks out…

Read more »

Investing Articles

Here’s how Rolls-Royce shares could hit £25 in 2026

If Rolls-Royce shares continue their recent performance, then £25 might be on the cards for 2026. Let's take a look…

Read more »

Departure & Arrival sign, representing selling and buying in a portfolio
Investing Articles

Prediction: in 2026 the red-hot Rolls-Royce share price could turn £10,000 into…

Harvey Jones can't believe how rapidlly the Rolls-Royce share price has climbed. Now he looks at the FTSE 100 growth…

Read more »