Stop saving and start investing! How the FTSE 100 could turn £100 per week into a £1m ISA

I think the FTSE 100 (INDEXFTSE:UKX) offers strong long-term growth potential.

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.

Investing £100 per week and ending up with a seven-figure portfolio may sound like a pipe dream to most people. However, it could be a much more attainable goal than it first seems due to the long-term growth potential of the FTSE 100.

By investing in a range of large-cap shares, holding them over the long run and reinvesting your dividends, you could end up with a £1m+ portfolio. By contrast, investing in a Cash ISA or savings account may mean that you experience disappointing returns that fail to improve your long-term financial situation.

FTSE 100 potential

The FTSE 100’s total annual returns since its inception 36 years ago have been around 9%. Assuming a similar rate of growth in future, a £100 investment in the index could be worth over £1m over a 34-year period. This assumes that dividends are reinvested, and that no capital is withdrawn from your portfolio.

With the FTSE 100 currently appearing to offer good value for money, its future returns could prove to be relatively impressive. For example, it has a dividend yield of 4.4%, which is above its long-term average, while major sectors such as resources, energy and financial services appear to offer many stocks that trade on low ratings compared to their historic averages. Over the long run, those valuations may revert towards their averages, which may lead to higher returns for investors in the FTSE 100.

Cash prospects

While the FTSE 100 could catalyse your portfolio’s performance, holding cash or investing in a Cash ISA may not. At the present time, savers may struggle to obtain an income return above 1.5%. Assuming such a rate of return over the same 34-year period discussed above, paying £100 per week into a savings account would lead to a total balance of £228,000.

Clearly, there is scope for interest rates to rise over the coming decades. But history shows that cash returns have lagged the stock market’s returns, due to the lower risk of cash, which may mean that a higher regular investment than £100 per week is required to generate a £1m+ portfolio.

Risk/reward

While the FTSE 100 is a riskier place to invest compared to cash, investors with a long-term outlook are likely to have sufficient time to enable their short-term paper losses to recover. This could mean that, while holding a modest amount of cash for emergencies is a sound move, focusing your capital on the FTSE 100 is a better idea when it comes to improving your long-term financial situation.

Of course, buying high-quality shares while they trade at low prices could enable you to beat the FTSE 100 and generate even higher returns. This could shorten the amount of time it takes to produce a £1m+ portfolio, and may lead to greater financial freedom in older age.  

Peter Stephens 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

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 »

Two female adult friends walking through the city streets at Christmas. They are talking and smiling as they do some Christmas shopping.
Investing Articles

Next impresses again, but could its shares be about to crash?

Next shares have leapt after the retailer raised its full-year profits guidance. But could the FTSE 100 retailer be running…

Read more »

Investing Articles

Time to buy, after Next shares are lifted by storming FY results?

Retail sector weakness is holding back Next shares, is it? Tell that to the fashion shoppers who've driven up full-year…

Read more »

Three signposts pointing in different directions, with 'Buy' 'Sell' and 'Hold' on
Growth Shares

Why the Barclays share price is currently its most undervalued in months

Jon Smith talks through why the Barclays share price has struggled in recent weeks, and flags up reasons why it…

Read more »

DIVIDEND YIELD text written on a notebook with chart
Investing Articles

10.7% yield! Should investors snap up Taylor Wimpey shares before they go ex-dividend on 2 April?

Harvey Jones is stunned by the double-digit yield available from Taylor Wimpey shares. But the FTSE 250 stock comes with…

Read more »

White female supervisor working at an oil rig
Investing For Beginners

Are investors taking a massive gamble with the Shell share price?

Jon Smith mulls the current state of play in the oil market and explains why he thinks further gains for…

Read more »

Young brown woman delighted with what she sees on her screen
Investing Articles

Stock market correction 2026: a rare chance to scoop up cheap UK shares?

The UK stock market's officially in a correction after a sharp drop in UK share prices, but our writer sees…

Read more »

Investing Articles

How much do you need in an ISA to aim for a £750 monthly second income?

Harvey Jones crunches the numbers to show how investors could aim for a high-and-rising second income from dividend-paying FTSE 100…

Read more »