3 common mistakes experienced investors should avoid

Avoiding these three errors could boost your portfolio returns.

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.

While many people find that they become better investors as they become more experienced, nobody is ever perfect. Even Warren Buffet, one of the most successful investors of all time, makes mistakes from time to time. Therefore, it is natural for all investors to have flaws which could hold back their portfolio returns.

With that in mind, here are three common mistakes which more experienced investors often make. Avoiding them could lead to a more profitable future for you and your investments.

Overconfidence

With the FTSE 100 having soared to an all-time high in recent months after a stunning Bull Run, many investors are likely to be in profit. In many cases, they will have been able to generate high returns at least partly due to their own skill and judgement. For example, they may have been able to discover a number of strong performers that have beaten their respective sectors and indexes in recent years.

However, there is a danger – especially during a bull market – for investors to become overconfident. This is perhaps to be expected, since they have enjoyed a prosperous period. But it can lead to too much risk being taken, and an insufficient focus on the potential weaknesses of a particular stock. As such, reminding oneself that market conditions will eventually change could be a prudent method to overcome this particular mistake.

Overinvesting

Linked to overconfidence is the idea of overinvesting. This also usually happens after a bull market has been in existence for a period of time. It is where an investor will see the high returns that have been on offer in recent months/years and decide that they need to invest a higher proportion of their wealth in the stock market.

While this can lead to even higher returns, it also leaves an investor in a less sustainable financial position. Should markets correct as they have done in recent weeks, it can mean an investor lacks cash to buy stocks at lower prices. And should there be a real-life emergency which requires capital, an investor who is 100% invested in the stock market may lack the cash to overcome it. As such, keeping some cash on hand could be a good idea.

Over-concentration

With some sectors having performed better than others in recent years, it is understandable that some investors will have high concentrations in specific industries. They may have even added to their winning shares in the hope of generating even higher levels of profitability in the long run.

Doing so can increase portfolio risk, since a high proportion of wealth in a small number of sectors may mean there is a lack of diversity in a portfolio. This can lead to higher volatility and greater loss in the long run. Therefore, ensuring that a portfolio has exposure to a range of stocks and sectors, no matter what the outlook is for the economy, could be a shrewd move.

More on Investing Articles

Group of young friends toasting each other with beers in a pub
Investing Articles

FTSE 100 shares: has a once-a-decade chance to build wealth ended?

The FTSE 100 index has had a strong 2025. But that doesn't mean there might not still be some bargain…

Read more »

Passive income text with pin graph chart on business table
Investing Articles

I asked ChatGPT for its top passive income ideas for 2026 and it said…

Stephen Wright is looking for passive income ideas for 2026. But can asking artificial intelligence for insights offer anything valuable?

Read more »

Woman riding her old fashioned bicycle along the Beach Esplanade at Aberdeen, Scotland.
Investing Articles

Here’s how a 10-share SIPP could combine both growth and income opportunities!

Juggling the prospects of growth and dividend income within one SIPP can take some effort. Our writer shares his thoughts…

Read more »

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

The stock market might crash in 2026. Here’s why I’m not worried

When Michael Burry forecasts a crash, the stock market takes notice. But do long-term investors actually need to worry about…

Read more »

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

Is this FTSE 250 retailer set for a dramatic recovery in 2026?

FTSE 250 retailer WH Smith is moving on from the accounting issues that have weighed on it in 2025. But…

Read more »

Young Black woman using a debit card at an ATM to withdraw money
Investing Articles

I’m racing to buy dirt cheap income stocks before it’s too late

Income stocks are set to have a terrific year in 2026 with multiple tailwinds supporting dividend growth. Here's what Zaven…

Read more »

ISA Individual Savings Account
Investing Articles

Aiming for a £1k passive income? Here’s how much you’d need in an ISA

Mark Hartley does the maths to calculate how much an investor would need in an ISA when aiming for a…

Read more »

Two business people sitting at cafe working on new project using laptop. Young businesswoman taking notes and businessman working on laptop computer.
Investing Articles

Is investing £5,000 enough to earn a £1,000 second income?

Want to start earning a second income in the stock market? Zaven Boyrazian breaks down how investors can aim to…

Read more »