How I’d invest £100 a month in UK shares to target a £600,000 portfolio

Investing even a small sum regularly can help build a sizable six-figure portfolio in the long run. It could even lead to an earlier retirement!

| More on:

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.

A senior woman and young girl help out in the greenhouse at the local farm.

Image source: Getty Images

Buying and holding UK shares for the long run can help investors build some substantial wealth. Even when only putting £100 into the stock market each month, it’s possible to grow a pretty impressive nest egg to retire on.

In fact, if investors start early enough, this could transform into a £600,000+ portfolio generating over £25,000 passive income!

Turning £100 into £600k

On average, the UK stock market’s delivered annualised returns of around 8%-10% a year. The FTSE 100‘s historically offered the lower end of this range, with the FTSE 250 tending higher. Yet, this higher performance has also come paired with significantly more volatility.

Nevertheless, when maximising returns is the priority, sticking with the UK’s flagship growth index makes more sense. So how long would it take to transform a £100 monthly investment into a £600,000 portfolio at a 10% annualised return? The answer – about 40 years.

YearsInvested CapitalPortfolio Value
5£6,000£7,744
10£12,000£20,485
20£24,000£75,937
30£36,000£226,049
40£48,000£632,408

Given that the average length of a career is around 45 years, putting aside £100 a month might be sufficient to open the door to a slightly earlier retirement. And by following the 4% withdrawal rule, investors could also continue to earn a £25,300 passive annual salary.

That’s terrific news for those who’ve just started working. But less so for those who’ve already been at it for a while and haven’t started putting money aside. Even more so considering that the process of building a £600,000 nest egg might end up taking even longer than expected. After all, just because the FTSE 250 has delivered near 10% returns in the past doesn’t mean it will continue to do so in the future.

So besides simply injecting more money into UK shares, how can investors still reach the £600,000 threshold on a shorter timeline?

Seeking higher returns

While the London Stock Exchange has a reputation for conservative investing, there are still plenty of high-growth opportunities for investors to capitalise on. One such example from my portfolio is Alpha Group International (LSE:ALPH).

The currency risk management and alternative banking company has been on quite a rampage over the last five years. In fact, the fintech stock’s doubled. Zooming out to its IPO in 2017 reveals a massive 770% total return for shareholders.

That means over the last seven years investors have reaped a 33.9% annualised return. And if £100 was invested each month at this rate, the journey to reaching £600,000 would take around half the time.

Sadly, this level of gargantuan growth’s pretty rare and isn’t likely to be sustained over the next decade-and-a-half. After all, Alpha Group’s now a £890m market-cap company. And while I remain optimistic about its long-term potential despite the risks and challenges it faces, expecting a near-34% annualised return is just unrealistic.

However, it goes to show that by picking individual stocks rather than mimicking an index, some tremendous market-beating gains can be achieved. And by hunting for Alpha-like UK shares, the journey to £600k could be significantly shortened.

In fact, even if only an extra 2% above the FTSE 250’s historical average is achieved, that’s still sufficient to wipe out five years from the waiting time.

Zaven Boyrazian has positions in Alpha Group International. The Motley Fool UK has recommended Alpha Group International. 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

British pound data
Investing Articles

The red lights are flashing again for Lloyds’ share price! Here’s why

Lloyds' share price continues to defy gravity. But Royston Wild thinks it's only a matter of time before the FTSE…

Read more »

Aston Martin DBX - rear pic of trunk
Investing Articles

Aston Martin shares are now only 41p!

Aston Martin shares just dropped to around the 41p mark! Is this a brilliant buying opportunity or a stock that…

Read more »

Artillery rocket system aimed to the sky and soldiers at sunset.
Investing Articles

Up 325% in 5 years! But are BAE System shares still a no-brainer buy?

BAE Systems shares would have been a brilliant buy five years ago. But could they still offer excellent returns if…

Read more »

Investing Articles

How much do you need to invest each month into FTSE 100 shares to aim for a million?

Simply by putting a few hundred pounds a month into FTSE 100 shares, how might someone aim to become a…

Read more »

Close-up as a woman counts out modern British banknotes.
Investing Articles

£10,000 invested in BAE shares at the beginning of 2026 is now worth…

Paul Summers tips his hat to those who invested in BAE Systems shares when markets opened back up in January.…

Read more »

A senior man and his wife holding hands walking up a hill on a footpath looking away from the camera at the view. The fishing village of Polperro is behind them.
Investing Articles

What size ISA do you need for £250-a-week retirement income?

Harvey Jones outlines the advantages of investing in a Stocks and Shares ISA rather than leaving money in cash, and…

Read more »

Mature Caucasian woman sat at a table with coffee and laptop while making notes on paper
Investing Articles

£5,000 invested in Legal & General shares 5 years ago is now worth…

Harvey Jones crunches the numbers to show how much an investor would have earned from Legal & General shares lately,…

Read more »

Investing Articles

Just check out the latest bumper forecasts for Lloyds, NatWest and Barclays shares

Harvey Jones says Barclays shares have had a terrific year and there could be more action to come. So what's…

Read more »