The billionaire Warren Buffett, whose stock picks have turned Berkshire Hathaway into one of the most successful conglomerates in the world, criticised Wall Street on Saturday, saying investors should “stick with low-cost index funds”.

The much-scrutinised annual letter to shareholders from the man many investors call “the Oracle of Omaha” also revealed that Berkshire Hathaway’s gain on its investment in Apple stands at more than $1.6bn, after shares of the iPhone maker surged.

Unlike last year, Buffett, a vocal supporter of Hillary Clinton, did not mention President Donald Trump by name. He did, however, talk up the vibrancy of American society and its inclusion of immigrants, one of the most polarizing issues under the Trump administration.

“One word sums up our country’s achievements: miraculous,” Buffett said. “From a standing start 240 years ago – a span of time less than triple my days on earth – Americans have combined human ingenuity, a market system, a tide of talented and ambitious immigrants, and the rule of law to deliver abundance beyond any dreams of our forefathers.”

In 2016, Buffett wrote that Trump was “dead wrong” to talk down America’s economic future and also emphasised the threat of climate change, which Trump has questioned.

This year, regarding Wall Street, Buffett wrote: “When trillions of dollars are managed by Wall Streeters charging high fees, it will usually be the managers who reap outsized profits, not the clients. Both large and small investors should stick with low-cost index funds.”

Buffett estimated that the search for outperformance has caused investors to “waste” more than $100bn over the past decade.