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

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.

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 stock American Express is flashing a bullish signal after breaking out, with earnings due next week. American Express stock wavered in buy range on Thursday. Also, American Express on Thursday announced it would pay a roughly $230 million settlement following a Department of Justice criminal wire fraud investigation.