My biggest investing mistake, and how you can avoid it

I’ve made plenty of mistakes in my investment career, but this one is undoubtedly the most costly.

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.

I’ve made all the common investing mistakes in my time and here are just some of them.

Too greedy

Never buy soaring growth stocks that have already risen to inflated values? I’ve done that. Some apparently inflated valuations turn out to be cheap and the shares keep rising — but not mine.

I made that mistake early on, in my growth investor phase. The strategy did no better than an index tracker overall, but with more heartache.

Become too attached to a stock and hang on to it despite the mounting evidence against it? I’ve been there too, letting emotional attachment triumph over cold hard fundamentals, and have lost money.

I’ve concentrated on buying and forgot to learn when to sell, and I’ve even been influenced by share price charts in the past. Name a mistake, and I’ve probably made it.

But even with all that, I’ve easily managed to beat cash saved in the bank, and I’ve had a lot of fun while doing it. And my biggest mistake is… not starting a lot sooner.

Time is your best friend

The thing is, it’s investing your cash in shares, reinvesting dividends every year, and doing that for decades that brings you success.

I was in quite well-paid jobs right from leaving university, but I spent my money and enjoyed it rather than stashing some away every month and buying shares. And it wasn’t until around 10 years later that I learned about the long-term prospects for the stock market. But what difference might my lost decade have made?

Let’s compare two individuals. One starts investing £500 per month in the stock market, and manages an average return of 6% per year. They start early and continue for 30 years. 

Over that time, assuming every year’s profits are reinvested and compounded (and not taken as dividends and spent), our young starter will have accumulated a nest egg to the value of approximately £490,000.

Our second investor, like me, wasted 10 years of investing opportunity before the light bulb switched on. How much do you think they’d need to invest every month to match our early-starter hero?

You might be shocked to learn that even investing twice as much every month, for the shortened period of 20 years, still wouldn’t quite make it. £1,000 per month invested in shares for that period, assuming the same 6% annual return, would bag approximately £456,000.

Sobering comparison

That’s a shortfall of £34,000, but the biggest surprise comes from comparing the total cash invested.

Our first investor has plonked down £500 per month for 30 years, which amounts to a total of £180,000 — and turning that into £490,000 is very pleasing result.

But our second investor, who has been stashing away twice as much money every month for 20 years, will have invested a total of £240,000. It will have cost them a full 50% more to achieve a poorer result.

The lesson is clear. You should start saving money every month and invest it in shares as soon as you can — and keep on doing so every month, while buying even more shares with any dividends you earn.

If you’re in the position I was in, or that of our second example investor here, you obviously can’t go back in time and start again. But you can start today and not waste any more time.

More on Investing Articles

Investing Articles

With BP shares boosted by Q1 results, how much higher can they go?

A big jump in profit in the first quarter put BP shares among the FTSE 100's upwards movers, with the…

Read more »

Three generation family are playing football together in a field. There are two boys, their father and their grandfather.
Investing Articles

How many Standard Life shares must an investor buy to give up work and live off the income?

Standard Life shares could be hiding one of the market’s most powerful long-term income engines — and the latest numbers…

Read more »

Businessman hand stacking money coins with virtual percentage icons
Investing Articles

Down 26% to under £17! What on earth’s going on with Greggs shares right now?

Greggs shares are trading at a deep discount to their ‘fair value’, despite record sales -- that gap could be…

Read more »

Mature black woman at home texting on her cell phone while sitting on the couch
Investing Articles

Barclays shares just fell 3% after Q1 results. Is this a buying opportunity?

Barclays shares fall on results day. Andrew Mackie digs into Q1 numbers, buybacks, and whether investors should actually be buying…

Read more »

Close-up of a woman holding modern polymer ten, twenty and fifty pound notes.
Investing For Beginners

£10k invested in the FTSE 100 at the start of the decade is now worth…

Jon Smith shows the historical return from parking money in a FTSE 100 tracker, but outlines the potential benefits from…

Read more »

A mature adult sitting by a fireplace in a living room at home. She is wearing a yellow cardigan and spectacles.
Dividend Shares

Cash ISA vs dividend shares: which builds wealth faster?

Jon Smith considers the growing interest in Cash ISA's and notes the pros and cons when thinking about allocating cash…

Read more »

National Grid engineers at a substation
Investing Articles

What on earth’s going on with the National Grid share price?

The National Grid share price has been on fire, but is there still more room for growth? Zaven Boyrazian explores…

Read more »

Person holding magnifying glass over important document, reading the small print
Investing Articles

1 ‘radioactive’ FTSE share that’s worth a second look

This former high-flying FTSE 100 stock has now crashed 63% inside five years. Why on earth would anyone consider buying…

Read more »