S&P 500 investors are playing it safer in 2025 — so Warren Buffett's careful stock-picking is in style again.

The first high-flying AI stock Warren Buffett secretly owns is industry-leading networking-solutions provider Broadcom (NASDAQ: AVGO). New England Asset Management closed out the third quarter with 19,855 shares of Broadcom, which has a present-day value of nearly $4.5 million.

Warren Buffett is widely considered one of the greatest investors ever because he has delivered excellent returns for a long time. The Oracle of Omaha's investing strategy was effective 10 years ago.

Has Warren Buffett given up on stocks amid overstretched valuations? That’s the big question, as the “Oracle of Omaha” has been a net seller in recent months.

Warren Buffett is known for his investing success, generating market-beating returns over the long run. As chairman, he's helped Berkshire Hathaway deliver a compounded annual gain of more than 19% over 58 years -- that's as the S&P 500 posted a compounded increase of about 10% during that period.

When I make reference to Buffett's favorite stock, I'm talking about none other than Berkshire Hathaway itself. Buffett has authorized the repurchase of $77.8 billion worth of Berkshire stock since 2018, which is more than twice the amount the conglomerate invested in Apple.

Warren Buffett’s Berkshire Hathaway has sold $133 billion worth of stocks in the first nine months of 2024. The company reduced its stakes in Apple, American Express, and Bank of America, which made up a large portion of its portfolio.