Share your opinion and earn yourself a free Motley Fool premium report!

We are looking for Fools to join a 75 minute online independent market research forum on 15th / 16th December.

To find out more and express your interest please click here

3 basic but costly ISA mistakes to avoid

This writer is trying to avoid a trio of mistakes that people commonly make with a Stocks and Shares ISA. Here’s why he wants to steer clear of them.

| More on:

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.

ISA coins

Image source: Getty Images

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.

A Stocks and Shares ISA can be a powerful platform for building wealth over the long term, even from a modest base.

But while rising share prices and dividends could help to create wealth in an ISA, there are also factors that can destroy it.

That is why I try to avoid this trio of common traps when investing.

Getting too excited about one share

Imagine this scenario.

You buy a share you think is brilliant and it goes up a lot. So you buy more – and it goes up further. Excited, you buy even more – and it goes up again.

This is both bad and good, in my view. Clearly the increase in value is good – so what’s bad? The lack of diversification in the ISA.

More and more money being put into one share makes the ISA less diversified. Meanwhile, that share’s rising value means it comes to represent a larger and larger percentage of the overall portfolio.

That can happen to anyone – Warren Buffett’s Apple stake came to dominate his portfolio at one point precisely because the price had risen so far.

Buffett then sold lots of Apple shares, although by hanging on to many he suggested that this was not because he had lost faith in the investment case.

No matter how compelling one share may seem, any smart investor always stays diversified. Even the best companies can run into unexpected business challenges.

Chasing yield regardless of its source

A lot of ISA investors (and I include myself in this) like the passive income potential of a portfolio stuffed with dividend shares.

With a £20k portfolio, the current average FTSE 100 yield of 3.4% would mean annual passive income streams of £680. But a 5% yield would mean £1,000, while a 10% yield would mean £2,000.

The appeal of high yields is easy to understand. It can be addictive.

But as an investor, it is important always to remember that dividends are never guaranteed.

So instead of fixating on a share’s current yield, I try to look at its business prospects and assess what sort of yield I think it may be able to support in future.

Throwing good money after bad

I recently sold all my shares in Boohoo Group (LSE: DEBS). That was a painful decision to make, as not only did I sell for much less than I originally paid, but I also had to consider why I had squandered some of the money in my ISA to buy such a dog.

The reason was that, when I bought, Boohoo had proven its business model, had previously been profitable, was sitting on spare cash and had a strong brand and large user base.

Some of those potential strengths are still true and could help fuel a turnaround. But Boohoo has had an awful few years, losing money hand over fist while battling a downwards sales trend.

Finally I decided to cut my losses. But maybe I should have done that after my first purchase, rather than buying more shares when the price fell.

Badly chosen shares are not the only way one can waste money in an ISA: paying unnecessary fees and charges is another.

So, it pays to pick smartly when using a Stocks and Shares ISA to try to build wealth.

C Ruane has no position in any of the shares mentioned. The Motley Fool UK has recommended Apple. 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

Warren Buffett at a Berkshire Hathaway AGM
Investing Articles

3 Warren Buffett investing ideas I plan to use in 2026

After decades in the top job at Berkshire Hathaway, Warren Buffett is preparing to step aside. But this writer will…

Read more »

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

Looking to earn a second income next year (and every year)? Here’s one approach.

Christopher Ruane explains how some prudent investment decisions now could potentially help set someone up with a second income in…

Read more »

Senior woman potting plant in garden at home
Investing Articles

Could a 10%+ yielding dividend share like this make sense for a retirement portfolio?

With a double-digit percentage yield, could this FTSE 250 share be worth considering for a retirement portfolio? Our writer weighs…

Read more »

Black woman using smartphone at home, watching stock charts.
Investing Articles

Forget Rigetti and IonQ: here’s a quantum computing growth stock that actually looks cheap

Edward Sheldon has found a growth stock in the quantum computing space with lots of potential and a really attractive…

Read more »

UK money in a Jar on a background
Investing Articles

Here’s a £3 a day passive income plan for 2026!

Looking for a simple and cheap plan to try and earn passive income in 2026 and beyond? Christopher Ruane shares…

Read more »

Blue NIO sports car in Oslo showroom
Investing Articles

NIO stock’s down 35% since October. Time to buy?

NIO stock has had a roller coaster year so far! Christopher Ruane looks at some of the highs and lows…

Read more »

Investing Articles

By December 2026, £1,000 invested in BAE Systems shares could be worth…

Where will BAE Systems shares be in a year's time? Here is our Foolish author's review of the latest analyst…

Read more »

Mature people enjoying time together during road trip
Investing Articles

Keen for early retirement with a second income from dividends? Here’s how much you might need to invest

Ditching the office job early is a dream of many, but without a second income, is it possible? Here’s how…

Read more »