4 mistakes many FTSE 100 investors will make in 2020

Panicking when the FTSE 100 (INDEXFTSE: UKX) falls is not the only mistake investors will make next year.

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.

Making mistakes is all part of investing. Even top investors such as Warren Buffett make mistakes at times. However, there are a number of basic errors a lot of investors make time and time again.

With that in mind, here’s a look at four I can guarantee many FTSE 100 investors will make next year.

Only owning a few stocks

One mistake many novice Footsie investors are likely to make next year is only owning a few stocks. There’ll be plenty of investors who own five stocks or less. 

The problem with only holding a few stocks is that it results in a high degree of stock-specific risk. If one or two of those stocks in a five-stock portfolio underperform, the overall portfolio value is going to take a large hit.

To reduce your risk, it’s therefore a good idea to diversify your money over many different stocks.

Not diversifying outside the FTSE 100

Another basic mistake is investors not diversifying their portfolios to include businesses outside the FTSE 100.

While the FTSE 100 index contains some brilliant companies, it’s not perfect. For example, it only contains large-cap stocks (many of which are struggling to grow) and it has very little exposure to the fast-growing technology sector. As a result, investment returns from the Footsie can be somewhat underwhelming at times.

Therefore to give yourself the best chance of generating decent investment returns, it’s a good idea to own some stocks outside the FTSE 100. This means mid-cap and small-cap stocks, as well as international stocks.

Panicking when the FTSE 100 falls

One mistake I can guarantee many investors will make next year is panicking when the FTSE 100 falls. This happens every time there’s stock market volatility.

Panic tends to lead to irrational decisions. To be a successful investor, you need to be able to stay calm and make rational decisions when stock market conditions are challenging.

Stock market weakness can also create amazing buying opportunities. Unfortunately, many investors miss out on these opportunities because they’re stuck in panic mode.

Putting too much focus on valuation

Finally, another mistake many FTSE 100 investors are likely to make next year is putting too much focus on stocks’ valuations (P/E ratios). They’ll buy stocks simply because they’re ‘cheap’.

Don’t get me wrong – a stock’s valuation is important. Yet putting too much focus on valuation can backfire on you. Cheap stocks are often cheap for a reason. And quite often, cheap stocks just keep falling and become even cheaper. Just looked at BT shares – they’ve been cheap for years now and continue to keep heading lower.

Ultimately, when picking stocks, it’s important to look at a number of different factors, including revenue and earnings growth, profitability, and balance sheet strength.

Edward Sheldon has no position in any 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

Investing Articles

Here are my top US stocks to consider buying in 2026

The US remains the most popular market for investors looking for stocks to buy. In a crowded market, where does…

Read more »

Investing Articles

£20,000 in excess savings? Here’s how to try and turn that into a second income in 2026

Stephen Wright outlines an opportunity for investors with £20,000 in excess cash to target a £1,450 a year second income…

Read more »

DIVIDEND YIELD text written on a notebook with chart
Investing Articles

Is a 9% yield from one of the UK’s most reliable dividend shares too good to be true?

Taylor Wimpey’s recent dividend record has been outstanding, but investors thinking of buying shares need to take a careful look…

Read more »

Snowing on Jubilee Gardens in London at dusk
Value Shares

Is it time to consider buying this FTSE 250 Christmas turkey?

With its share price falling by more than half since December 2024, James Beard considers the prospects for the worst-performing…

Read more »

A young black man makes the symbol of a peace sign with two fingers
Investing Articles

2 FTSE shares experts think will smash the market in 2026!

Discover some of the best-performing FTSE shares of 2025, and which ones expert analysts think will outperform in 2026 and…

Read more »

Close-up image depicting a woman in her 70s taking British bank notes from her colourful leather wallet.
Investing Articles

Every pound I invested in this FTSE 100 growth stock last year is now worth £3

Mark Hartley is astounded by the growth of one under-the-radar FTSE stock that’s up 200%. But looking ahead, he has…

Read more »

Tabletop model of a bear sat on desk in front of monitors showing stock charts
Investing Articles

Is the S&P 500 heading for a stock market crash?

The S&P 500's surged by double digits yet again in 2025, but can this momentum continue in 2026, or are…

Read more »

Rolls-Royce's Pearl 10X engine series
Investing Articles

£2,000 invested in Rolls-Royce shares 3 years ago is now worth…

Anyone who had the courage to buy Rolls-Royce shares three years ago, and has held on to them, has made…

Read more »