Berkshire sold 20.7 million of those shares in the third quarter of 2024, but its 86.4 million remaining shares are still worth $949 million and give it a 1.8% stake in the company. Berkshire's stake in Nu only accounts for 0.3% of its entire portfolio, but the Latin American bank is still growing much faster than its brick-and-mortar competitors.

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

Arguably the world's greatest stock picker isn't picking many stocks these days. Warren Buffett has been a net seller of stocks for eight consecutive quarters. There's a reason Buffett isn't buying many stocks -- and it's the same reason he ranks among the greatest investors of all time.