FTSE 100 investing: are you making this key mistake?

Investing in FTSE 100 (INDEXFTSE: UKX) stocks? Be careful not to make this mistake as it could hurt your 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.

When it comes to investing in the FTSE 100, there are plenty of common mistakes a lot of investors make on a regular basis. For example, buying high and selling low, panicking when the market falls, and not diversifying are three of the most typical.

Yet another mistake that could be just as dangerous is putting too much focus on price-to-earnings (P/E) ratios when picking stocks. Could this be hurting your performance?

The P/E ratio

The P/E ratio is widely-used in stock market analysis. A simple ratio which shows the price of a stock per £1 of earnings, the ratio gives an indication of whether value is on offer. The general idea is that the lower the P/E ratio, the more value that’s on offer.

The P/E ratio does have several things going for it. For starters, it allows investors to compare valuations for different companies. Secondly, it’s very easy to calculate (share price divided by earnings per share). However, the ratio is not perfect and it’s important to realise a stock with a low P/E isn’t necessarily a bargain. Similarly, a stock with a high P/E ratio shouldn’t necessarily be avoided.

Focus on quality

One problem with the P/E ratio is that it doesn’t tell you anything about a stock’s ‘quality.’ For example, it tells you nothing about revenue or earnings growth, or the company’s financial health. And, like many things in life, when it comes to stocks, sometimes you’re better off paying a little more for a higher-quality stock than investing in a low-quality stock simply because it’s cheap. As Warren Buffett says: “It’s far better to buy a wonderful company at a fair price than a fair company at a wonderful price.”

Cheap stocks can stay cheap

The problem with cheap stocks that have low P/E ratios is that they’re often cheap for a reason. Perhaps earnings are declining or a dividend cut is on the horizon. And cheap stocks can often stay cheap (and get even cheaper) for a long time, which can really hurt your returns.

At the same time, stocks with high P/E ratios can sometimes deliver amazing returns for investors, despite their high valuations. Yes, a high P/E leaves less margin for error, but ignoring a stock just because it’s expensive could be a mistake.

For example, look at FTSE 100 stocks Diageo and Unilever which have been expensive on the basis of their P/E ratio for years now. These two are up 25% and 19%, respectively, over the last year.

By contrast, look at British American Tobacco and ITV. These two have been cheap for years, yet both have performed terribly over the last 12 months returning -20% and -37%, respectively.

The takeaway here is that while the P/E ratio can be useful, it’s not perfect, and putting too much focus on it could be a mistake. When it comes to stock picking, it’s important to look at a broad range of factors and not just valuation.

Edward Sheldon owns shares in Diageo, Unilever and ITV. The Motley Fool UK owns shares of and has recommended Unilever. The Motley Fool UK has recommended Diageo and ITV. 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

I asked ChatGPT to settle the ISA v SIPP debate once and for all. It said…

Instead of working out whether an ISA or SIPP is the better tax wrapper, Harvey Jones called the robots in.…

Read more »

Middle-aged white male courier delivering boxes to young black lady
Investing Articles

Amazon shares: overpriced or a possible bargain?

Christopher Ruane thinks Amazon shares look pricier than he normally likes -- but also reckons they could be a potential…

Read more »

Female Tesco employee holding produce crate
Investing Articles

In a jittery market, could Tesco shares be a defensive choice?

Could Tesco shares be a safe haven in nervous markets, given that consumers always need to eat? Our writer is…

Read more »

British coins and bank notes scattered on a surface
Investing Articles

How much might £10,000 in Rolls-Royce shares soon be worth? Let’s ask the experts

Do Rolls-Royce shares look like a good buy after recent price falls? City analysts still appear bullish, but global events…

Read more »

Queen Street, one of Cardiff's main shopping streets, busy with Saturday shoppers.
Investing Articles

Take a deep breath! £10,000 invested in Greggs shares a year ago is now worth…

Someone who bought Greggs shares a year ago is nursing a paper loss. Our writer digs into the reasons why…

Read more »

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

Whatever happened to the stock market crash?

The stock market refuses to crash, despite the Iran war. But Harvey Jones says lots of FTSE 100 shares have…

Read more »

Petrochemical engineer working at night with digital tablet inside oil and gas refinery plant
Investing Articles

BP’s share price will keep surging in 2026, according to this broker

BP’s share price is in a strong upward trend right now. And one City brokerage firm seems to believe that…

Read more »

Picture of an easyJet plane taking off.
Investing Articles

These 4 red flags mean I’m avoiding easyJet shares like the plague!

easyJet shares have slumped by around a quarter during the past month. Does this represent a dip-buying opportunity? Royston Wild…

Read more »