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.

Want to retire wealthy? Stop making this one investment mistake

Are you making this one critical mistake that could be holding back your retirement plans?

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.

Every investor has the tools at their disposal to make a fortune in the stock market. The problem is, while the tools are there, most investors make severe mistakes throughout their investing career, which cost them dearly. 

And there’s one crucial mistake that’s more damaging than all of the others put together. 

XXX

Rule one: Don’t lose money 

The most prominent mistake investors tend to make is losing money. At first, this might seem like an obvious statement to make. No one wants to lose money, and if there was a way to invest that is 100% risk-free, I’m sure every investor would jump at the chance. 

However, there’s a bit more to this statement than first meets the eye. 

You see, a large percentage of investors believe that volatility defines risk. The more volatile the stock, the more risk it has. But that isn’t the right way of thinking about the market. Instead, the world’s best investors define risk as the chance of losing 100% of your invested capital. 

The trick is to focus on how much you could lose from any investment, not how much you could gain. For example, that AIM mining stock might be worth 20 times its value IF it strikes gold. But what are the chances of everything going to plan? 

According to one set of analysts, the percentage of small mining companies that can successfully find, explore, develop a mine and start producing, is around 2%. So, in this scenario, you have a 98% chance of losing money and a 2% chance of making money. 

This is an imperfect example, but I think it’s a great way of showing how vital it is to consider how much you stand to lose with investment opportunity before taking the plunge. 

Twice as hard 

Another thing to consider with losses is that it’s twice as hard to make money back you’ve lost. If that AIM mining stock falls 60%, and you lose 60% of your capital, it will take a return of 150% to make your money back. 

If the investment is a complete disaster and you lose 98% of your hard earned money, to get back to the starting point, you’ll have to find an investment that produces a return of 4,900%! That’s virtually impossible. 

Conclusion 

So, how can you avoid breaking investing’s rule number one? The best way is to stick to established businesses and FTSE 100 constituents are a great example. Royal Dutch Shell, for example, has been producing returns for investors for more than seven decades. British American Tobacco has a similar record. The company’s share price might have declined over the past few months, but the risks of investors losing everything are slim. 

Another alternative is to use a simple index tracker fund. A FTSE 250 fund gives you instant exposure to the UK’s top 250 listed companies. This diversification means that the chances of investors suffering a 100% loss is virtually zero. 

Put simply, it’s possible to avoid investment losses if you avoid the riskiest companies, and stick with the market’s long-term winners. 

Rupert Hargreaves owns shares in Royal Dutch Shell and British American Tobacco. 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 »