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.

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 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.

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.

Warren Buffett is widely considered the greatest investor. From 1965 through 2023, his conglomerate, Berkshire Hathaway, delivered an astounding 4,384,748% total return to shareholders, or nearly 20% on an annualized basis.