It's no secret that investing guru Warren Buffett loves Coca-Cola (KO) and American Express (AXP -0.62%) stocks. Although he's generous with his investing advice, he doesn't typically address specific positions in the Berkshire Hathaway portfolio. But he has been singing these two companies' praises for years.

He was touting them again in his annual shareholder letter released in late February, giving investors another peek into his approach to investing.

Not big on newcomers

Despite the fact they're operating in completely different industries, Buffett groups Coca-Cola's and American Express' stocks together. They're both old and established -- American Express has been around since 1850, while Coca-Cola has been operating since 1886. Buffett joked that "Berkshire is not big on newcomers."

These are Berkshire Hathaway's longest-held equity positions. They are also the second and third-largest positions in the portfolio behind Apple's gargantuan percentage, with American Express accounting for 8.9% of the total and Coca-Cola accounting for 6.6%.

Both of these companies have a core business that has been incredibly successful for more than a century. He acknowledges that they've each tried to branch into new side hustles that haven't worked out, but their main businesses have flourished, and, as he says, they "travel."

As their products have worked themselves across the globe, their names have become synonymous with their core businesses, building strong, resilient brands. And both of them market products and services that are always in demand. In fact, he calls them "timeless essentials of our world."

Last year, Buffett used these two companies to illustrate the value of a strong, established business that pays a dividend. Buffett made more than $1 billion in dividends from them in 2022, and since he hasn't sold any and they both raised their dividends last year, he made even more in 2023. He expects that to continue in 2024, and he has no intention of selling a share of either stock.

Buffett said that Berkshire Hathaway's percentage of American Express' earnings in 2023 was more than the total cost of buying American Express stock.

How are they doing today?

American Express and Coca-Cola both closed out a challenging 2023 on a high note. American Express revenue increased 11% year over year, with a 27% increase in earnings per share (EPS). Coca-Cola's sales increased 6% year over year, with a 13% increase in EPS. Both companies' CEOs discussed their increased brand value as a factor in their performance.

Coca-Cola is a Dividend King and raised its dividend for the 62nd consecutive year this month. American Express has paid dividends since 1989. It hasn't been as consistent with its increases, but it's made up for that with large increases -- more than double Coca-Cola's over the past 10 years.

Take this approach and run with it

Buffett sums up the lesson he's learned from holding onto these stocks for decades: "When you find a truly wonderful business, stick with it. Patience pays, and one wonderful business can offset the many mediocre decisions that are inevitable."

There's so much to take from that statement, and Buffett's wisdom doesn't need any elaboration. Investors can use it to consider what wonderful businesses they've integrated with or researched that have staying power. The key element, as Buffett has reiterated many times, is to focus on the business and not the stock movement.