We have some exciting news to share! The Motley Fool UK has now become The Twelfth Magpie -- an independent, UK-owned company, led by our long-serving UK management team — Mark Rogers, Chris Nials and Heather Adlington. In practical terms, it’s the same team you know, now fully focused on serving our UK readers and members.

Just as importantly, our approach remains unchanged: long-term, jargon-free, and on your side. This site is our new home, and there will be extra tweaks made across the coming few days as we settle in. So if anything looks a little off, please bear with us!

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.

Here’s how I’d invest £20k to build a million pound Stocks and Shares ISA

Make this year’s £20k Stocks and Shares ISA allowance the start of your journey to build a million pound portfolio.

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.

What does the stock market do best? Turn relatively small amounts of money into much bigger amounts over time.

We are now entering the ISA season, when people look to use their annual tax-free allowance before it expires at midnight on 5 April. This year, you can invest up to £20k in a Stocks and Shares ISA, to help build your wealth. If you leave that in the market for the long term, and top it up whenever you have money to spare, you could ultimately build a £1m investment portfolio, and transform your retirement prospects.

XXX

I know investors are worried about the coronavirus, with the FTSE 100 falling sharply this morning. Nobody knows what impact it is going to have, creating uncertainty.

The problem is, if you wait until the outlook is sunny and bright, you will never invest money in the market, because there are always clouds on the horizon. Some people have spent the last decade shying away, and if they left their money in cash, they will have paid a heavy price in lost share price growth and dividend income.

Put your money to work today

The FTSE 100 and FTSE 250 both look promising right now, as the UK nears a Brexit resolution, and overseas investors take notice.

I’m particularly keen on the FTSE 250 right now. This is packed with medium-sized British companies that have greater exposure to the domestic economy, whereas FTSE 100 blue-chips generate three-quarters of their earnings overseas. These have been knocked by the strengthening pound, as this reduces the value of their dollars, euros and rupees when converted back into sterling.

The FTSE 250 has delivered a total return of 48.9% over the last five years, against 32.3% for the FTSE 100. 

Thrash the returns on cash

One reason shares are so rewarding is that they pay dividend income as well as generating capital growth, which wise investors pay straight back into their portfolios to buy further stocks or fund units. Currently, the FTSE 350 yields 4.24%, three times the amount you will get on the best Cash ISA.

This winning combination of share price growth and dividend income, is what will turn your £20k into a far mightier amount. If the FTSE 250 maintains its long-term average return of 9% a year, your money would grow to around £113,000 in 20 years’ time, and an astonishing £628,188 over 40 years, the average length of time over which people invest for their retirement.

To hit the million mark, you should aim to use next year’s ISA allowance, and the next year’s too, whenever you have money to share.

There are many undervalued shares on the market right now, and a quick search on the Fool website will throw up plenty of opportunities.

Look for companies with strong balance sheets, loyal customers, steady cash flows, and a track record of increasing dividends. These are the type of stocks that can help you build a £1m portfolio. Your £20k is the start of something much bigger.

Harvey Jones has no position in any of the shares mentioned. 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

Friends and sisters exploring the outdoors together in Cornwall. They are standing with their arms around each other at the coast.
Investing Articles

£503 buys 14 shares in this FTSE 250 stock that returned 23.9% annually for the last 15 years

This FTSE 250 stock has averaged a huge return for 15 years. At today's price, £503 buys 14 shares. But…

Read more »

Black woman using loudspeaker to be heard
Investing Articles

£1,000 buys 25 shares in this FTSE 100 stock that’s returned 29.2% annually for the last 10 years

This FTSE 100 mining stock has returned close to 30% a year for a decade. At 3,995p, £1,000 buys 25…

Read more »

Female student sitting at the steps and using laptop
Investing Articles

Down 47%, is this growth stock finally worth buying in May?

With a £288m order book and a hidden pipeline of defence and nuclear contracts, is this growth stock now too…

Read more »

House models and one with REIT - standing for real estate investment trust - written on it.
Investing Articles

2 REITs yielding 7%+ to consider for passive income in 2026

A REIT backed by the NHS and another backed by Tesco and Sainsbury's with both yielding 7%+. Here's why I'm…

Read more »

Woman riding her old fashioned bicycle along the Beach Esplanade at Aberdeen, Scotland.
Investing Articles

Just 97 shares of this UK dividend stock generate £238 in passive income

A 5.7% yield, £238 in passive income from just 97 shares, and one of the most divisive dividend stocks on…

Read more »

ISA coins
Investing Articles

£10,000 in an ISA generates a second income of…

The London Stock Exchange is home to some of the world's most generous dividends. But how big a second income…

Read more »

Shot of a senior man drinking coffee and looking thoughtfully out of a window
Investing Articles

Expert recommendations: 2 top income stocks yielding 7%+!

With yields of 7.2% and 7.8% respectively, these two income stocks are catching the eyes of institutional analysts. Should investors…

Read more »

Illustration of flames over a black background
Investing Articles

3 top income-focused stocks to buy in May 2026, according to experts

Looking for a stock to buy for income in May 2026? Experts have flagged these three UK dividend shares as…

Read more »