Some billionaire investors follow similar strategies. They build large, diversified portfolios. They frequently move in and out of stocks. But not Bill Ackman. His Pershing Square Capital Management hedge fund currently owns only 12 stocks -- and two of them are different share classes offered by the same company.
Ackman's portfolio isn't very diversified, either. Around 39% of Pershing Square's holdings focus heavily on artificial intelligence (AI). The billionaire loaded up on two AI stocks, in particular, in the fourth quarter of 2025.
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Amazon: Dominating two massive markets
Pershing Square already owned a stake in Amazon (AMZN +3.23%) going into the fourth quarter of 2025. Ackman first initiated a position in the stock a few months earlier. However, increased his hedge fund's position in Amazon by a whopping 65% in Q4.
Why does Ackman like Amazon so much? The company dominates two massive markets -- e-commerce and cloud services.
NASDAQ: AMZN
Key Data Points
Ackman is highly impressed with Amazon's e-commerce business. He believes that its profitability could nearly double as the company expands its higher-margin advertising revenue and continues to automate operations. However, he seems to be most interested in Amazon Web Services' AI opportunities.
The billionaire investor understands that AWS' impressive growth remains constrained by capacity constraints. Ackman predicts that AWS will be able to easily monetize its substantial infrastructure investments as customers increase their AI inference workloads.
Meta Platforms: An AI Value Play
Ackman initiated only one new position in Q4, and it was a doozy. Pershing Square scooped up 2.7 million shares of Meta Platforms (META +2.27%) valued at $1.8 billion, making Meta Platforms 11.4% of the hedge fund's total portfolio.
There's no secret why Ackman loaded up on Meta stock. In Pershing Square's annual investor presentation, he stated, "We believe Meta's current share price underappreciates the company's long-term upside potential
from AI and represents a deeply discounted valuation for one of the world's greatest businesses."
NASDAQ: META
Key Data Points
Meta may not look like a value stock right now, with its shares trading at 22.5 times forward earnings. However, the stock was lower throughout much of Q4, when Pershing Square bought it, than it is now. More importantly, Ackman thinks that Meta's core advertising business is relatively cheap, excluding the losses from the company's Reality Labs segment, which focuses on wearables and augmented reality.
AI continues to help Meta monetize content on its social media platforms more effectively. And with 3.58 billion daily active users, the company has a massive audience that is highly appealing to advertisers.
Should you buy Amazon and Meta, too?
Most investors will probably feel anxious about concentrating their money in only 12 stocks as Ackman has. However, I think that the billionaire's decision to load up on Amazon and Meta Platforms was smart.
AWS remains the king of AI infrastructure. I'm confident that Amazon's enormous capital expenditures in expanding its data centers will pay off handsomely. I also like the company's move into satellite internet services with Leo and its plans to acquire Globalstar (GSAT +1.10%). Amazon still has plenty of room to grow in e-commerce as well, in my view.
Meta Platforms' core advertising business remains a cash cow. The company has positioned itself as a leader in open-source AI with its Llama large language model (LLM). Meta is leading the smart glasses market with its two generations of Ray-Ban Meta AI Glasses. Its initiative to develop artificial superintelligence (ASI), AI that not only matches but surpasses human intelligence across every field, including creativity, problem-solving, and more.
I don't think investors should buy shares of Amazon and Meta just because a famous billionaire did. But buying these two AI stocks for the same reasons Ackman did is another story altogether.
