Warren Buffett's Berkshire Hathaway is betting on companies like Apple, Goldman Sachs and American Express for the long run, the "Oracle of Omaha" said in his annual letter to shareholders released Saturday.

The letter showed Berkshire's investment in Apple was worth more than $40 billion in terms of market value at the end of 2018. Berkshire's investments in Goldman Sachs and American Express were worth $3.13 billion and $14.45 billion, respectively.

Buffett said that he and Charlie Munger, Berkshire's vice chairman, don't view these holdings "as a collection of ticker symbols – a financial dalliance to be terminated because of downgrades by 'the Street,' expected Federal Reserve actions, possible political developments, forecasts by economists or whatever else might be the subject du jour."

"What we see in our holdings, rather, is an assembly of companies that we partly own and that, on a weighted basis, are earning about 20% on the net tangible equity capital required to run their businesses. These companies, also, earn their profits without employing excessive levels of debt," Buffett added.

His investments in 2018 did not have a great year because of the market rollover in the fourth quarter, but the long-term investor remains unfazed by short-term setbacks. Buffett noted in the letter that Berkshire suffered a $20.6 billion loss "from a reduction in the amount of unrealized capital gains that existed in our investment holdings."

Overall, Berkshire's common stock investments totaled $172.75 billion in market value at the end of 2018, up from $170.54 billion at the end of 2017.

Below is the full list of Berkshire's common stock investments at the end of 2018: