Meet Billionaire Bill Ackman's Newest Artificial Intelligence (AI) Stock, Which I Predict Will Become Wall Street's First $5 Trillion Company (Hint: It's Not Nvidia)

About a month and a half into each new quarter, every institutional fund that manages more than $100 million in qualifying assets is required to file a Form 13F with the Securities and Exchange Commission (SEC). The 13F documents all the investments the fund holds at the end of the prior quarter. Looking at these filings can be quite interesting for retail investors, as they show what Wall Street's high-profile investors have been up to recently.

Billionaire investor Bill Ackman founded hedge fund Pershing Square Capital Management, and serves as its CEO. Pershing Square's latest 13F, filed a couple of weeks ago, didn't contain many surprises. But in the days since, the public has gotten word of Ackman's latest investment.

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What stock did Bill Ackman just buy?

According to recent news reports, Pershing Square has initiated a position in Amazon (NASDAQ: AMZN). From what's been reported so far, it sounds like Pershing Square started buying shares of the e-commerce and cloud computing giant in April. Because that was after the end of the first quarter, the position was not reported in the hedge fund's most recent 13F.

As of the closing bell on May 27, shares of Amazon were down roughly 6% in 2025.

As the chart above shows, Amazon's year-to-date decline appears to have bottomed in April when the stock market as a whole took a massive hit following President Donald Trump's "Liberation Day" tariffs announcement on April 2.

Ackman likely started buying the dip following that tariff-driven sell-off.

Image Source: Getty Images.

Why might Ackman like Amazon so much?

When it comes to megacap artificial intelligence (AI) stocks, names such as Microsoft, Apple, Nvidia, or Tesla might come to mind first.

There are many reasons growth investors might want to own any of those stocks. However, one thing that ties them together to some degree is that each of their empires hinges on a particular business.

For example, while Microsoft is a diversified tech giant with offerings that span the personal computing, video game, social media, and cloud infrastructure spaces, its Azure cloud platform is overwhelmingly the driving force behind its growth narrative.

Apple sells a number of consumer electronics devices and offers numerous services, but analysts tend to index it based on the performance of the iPhone. This same dynamic can be applied to Tesla as Wall Street is focused on the performance of the electric vehicle (EV) business.

Lastly, while Nvidia also has a fairly diverse business in the chip sector, the majority of its growth has been coming from its data center GPU business. Hence, any news relating to the demand for data center AI chips can have an impact on the stock.

I don't see Ackman's decision to scoop up Amazon stock as a coincidence. As a reminder, Pershing Square already owns a meaningful position in another Magnificent Seven stock: Alphabet.

Alphabet has built a true ecosystem. It dominates internet search traffic thanks to properties such as Google and YouTube. Moreover, Alphabet has its own cloud infrastructure business that competes with Microsoft and Amazon. And in addition, the company has developed a number of competing AI-powered services in the realms of workplace productivity and cybersecurity, among others.

Alphabet's diversified business model relative to its peers is what I believe initially attracted Ackman. When you layer on top of that the fact Alphabet is trading at a meaningful discount to other members of the Magnificent Seven, the stock becomes even more appealing.

To me, Amazon is another version of Alphabet. The company has a broad ecosystem that includes e-commerce, cloud computing, logistics, subscriptions, advertising, streaming, brick-and-mortar shopping, and more.

On the AI front, Amazon is building its own custom silicon and investing heavily into data center infrastructure.

How Amazon could become a $5 trillion company

I recently wrote an article in which I broke down why I think Amazon could become Wall Street's first $5 trillion stock. That thesis hinges on two core ideas.

First, Amazon's investments in AI have only just started to bear fruit. The most obvious area where investors can see accelerated growth right now is in the company's cloud unit, Amazon Web Services (AWS).

However, similar to Alphabet, Amazon has a unique ability to stitch together its various businesses through the power of AI. Amazon could be on the brink of meaningful sales growth and profit margin expansion across its entire ecosystem, reducing its reliance on the strength of AWS.

The second pillar supporting a bullish outlook for Amazon is the potential for investors to apply a premium valuation to its stock should the company start generating superior sales and earnings growth relative to the competition.

In the interim, though, Amazon stock looks reasonably valued right now, and investors with long time horizons should consider following Ackman's lead.

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Suzanne Frey, an executive at Alphabet, is a member of The Motley Fool's board of directors. John Mackey, former CEO of Whole Foods Market, an Amazon subsidiary, is a member of The Motley Fool's board of directors. Adam Spatacco has positions in Alphabet, Amazon, Apple, Microsoft, Nvidia, and Tesla. The Motley Fool has positions in and recommends Alphabet, Amazon, Apple, Microsoft, Nvidia, and Tesla. The Motley Fool recommends the following options: long January 2026 $395 calls on Microsoft and short January 2026 $405 calls on Microsoft. The Motley Fool has a disclosure policy.