5 investment principles Warren Buffett applies

Christopher Ruane outlines five key investment lessons he applies to his own investing that he learnt from Warren Buffett’s example.

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.

One of the most legendary investors of all time is Warren Buffett. He is famous not just for buying companies but also picking individual stocks and shares.

As an investor I think I can learn a lot from Buffett. Here are five principles he applies when investing.

Invest in what you understand

Buffett is focussed on industries he understands, such as insurance, retail, and transportation. Instead of trying to find the largest possible return by widening his search field, Buffett only invests in shares of companies when he feels comfortable that he knows how its industry works. That doesn’t mean he doesn’t still make some bad choices, of course. But it stops him from falling into a common investing mistake, of buying shares in a company without understanding what it does in detail.

Size matters

Another interesting facet of Buffett’s investment approach that often isn’t discussed is that he tends to shun investing in shares of small companies. Many of his key holdings, such as Apple, American Express, and Bank of America, are huge listed companies.

Sometimes it is harder for a massive company to sustain growth than a smaller one. So why does Buffett focus on large companies? One explanation is that he is deploying vast sums of cash, so only large companies offer enough opportunity to meet his investment objectives. Focussing on finding just a handful of companies in which to invest can free up research time compared to looking into hundreds of different small firms.

Warren Buffett on management

As an investor, Warren Buffett certainly appreciates good management. Indeed he often publicly compliments executives whose work he appreciates. But he doesn’t buy shares purely because he likes a company management. As he pithily said, “I try to invest in businesses that are so wonderful that an idiot can run them. Because sooner or later, one will.”

In practice, what that means is that he looks for companies with a competitive advantage distinct from its top talent. For example, that could be a proprietary product as with Coca-Cola, or an entrenched business ecosystem which is hard to replicate, like American Express enjoys.

Watching for red flags

I find Buffett’s approach to risk management interesting too. Some investors weigh pros and cons, and if the potential returns seem good enough, have a high tolerance for risk. Buffett, one of the most successful investors in history, doesn’t do that. He walks away from a company even if there’s a single red flag that’s alarming enough. When Lehman Brothers wanted Buffett to invest in their failing business, he took an evening to read their publicly available financial filings and that was already enough for him to walk away from any deal.

Warren Buffett’s eggs in different baskets

Buffett also follows another form of risk management: he diversifies. While he owns some great seeming shares, Buffett is always careful to make sure his portfolio is not too dependent on any single company. That is a principle I apply in my own investment decisions too.

Christopher Ruane has no position in any shares mentioned. Bank of America is an advertising partner of The Ascent, a Motley Fool company. American Express is an advertising partner of The Ascent, a Motley Fool company. The Motley Fool UK owns shares of and has recommended Apple. The Motley Fool UK has recommended the following options: long March 2023 $120 calls on Apple and short March 2023 $130 calls on 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

Investing Articles

Is 2026 the year the Diageo share price bounces back?

Will next year be the start of a turnaround for the Diageo share price? Stephen Wright looks at a key…

Read more »

Investing Articles

Here’s my top FTSE 250 pick for 2026

UK investors looking for under-the-radar opportunities should check out the FTSE 250. And 2026 could be an exciting year for…

Read more »

Yellow number one sitting on blue background
Investing Articles

Here’s my number 1 passive income stock for 2026

Stephen Wright thinks a 5.5% dividend yield from a company with a strong competitive advantage is something passive income investors…

Read more »

Thoughtful man using his phone while riding on a train and looking through the window
Investing Articles

Should I sell my Scottish Mortgage shares in 2026?

After a strong run for Scottish Mortgage shares, our writer wonders if he should offload them to bank profits in…

Read more »

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

Down 35%! These 2 blue-chips are 2025’s big losers. But are they the best shares to buy in 2026?

Harvey Jones reckons he's found two of the best shares to buy for the year ahead, but he also acknowledges…

Read more »

A senior man and his wife holding hands walking up a hill on a footpath looking away from the camera at the view. The fishing village of Polperro is behind them.
Investing Articles

State Pension worries? 3 investment trusts to target a £2.6m retirement fund

Royston Wild isn't worried about possible State Pension changes. Here he identifies three investment trusts to target a multi-million-pound portfolio.

Read more »

Smiling white woman holding iPhone with Airpods in ear
Dividend Shares

4 dirt-cheap dividend stocks to consider for 2026!

Discover four great dividend stocks that could deliver long-term passive income -- and why our writer Royston Wild thinks they’re…

Read more »

Young mixed-race woman jumping for joy in a park with confetti falling around her
Investing Articles

These fabulous 5 UK stocks doubled in 2025 – can they do it again next year?

These five UK stocks have more than doubled investors' money as the FTSE 100 surges. Harvey Jones wonders if they…

Read more »