Microsoft is a major player in AI through its partnership with OpenAI and its Azure Cloud infrastructure. Citadel sold much of its Microsoft shares earlier this year, amid broader shifts in its investing strategy.

Interestingly, while Nvidia (NASDAQ: NVDA) and Taiwan Semiconductor (NYSE: TSM) are both positioned to benefit from demand for artificial intelligence (AI) infrastructure, Griffin bought one stock and sold the other in the third quarter.

Ken Griffin is arguably one of the most successful investors of all time. He made a name for himself when he shorted stocks just ahead of the 1987 market crash that came to be known as "Black Monday." His profits last year topped $7 billion as his returns of roughly 15% outpaced many of his peers.