Adam Spatacco, The Motley Fool

Sat, Jun 28, 2025, 6:00 AM5 min read

• Earlier this year, Bill Ackman bought a megacap AI stock -- joining Warren Buffett as a high-profile shareholder.

• Ackman and Buffett are both value investors, making the timing of Ackman's purchase particularly brilliant.

• While the markets have been moving higher over the last several weeks, Amazon remains my top pick.

• 10 stocks we like better than Amazon ›

Bill Ackman is a billionaire investor and serves as CEO to the hedge fund Pershing Square Capital Management. Throughout the artificial intelligence (AI) revolution, Pershing Square's primary exposure to the stock market's latest megatrend has been through a position in Alphabet.

Recently, however, Ackman made headlines after it was revealed that Pershing Square complemented its Alphabet position with another member of the "Magnificent Seven": Amazon (NASDAQ: AMZN). Interestingly, Amazon is one of the few technology stocks featured in Warren Buffett's portfolio at Berkshire Hathaway.

Let's explore why billionaire investors like Buffett and Ackman may have taken a liking to Amazon. Moreover, I'll break down why the e-commerce and cloud computing giant is my top pick among AI stocks.

Ackman and Buffett built their fortunes in different ways. Buffett is best known for building positions in globally recognized brands and holding onto these stocks over the course of many years or even decades.

In addition, many of Buffett's most lucrative investments have come from companies that consistently buy back stock or pay a dividend. Lastly, Buffett generally sticks to industries such as financial services, energy, and consumer goods -- rarely exposing Berkshire to more volatile markets such as the technology sector.

On the other hand, Ackman tends to be a bit more industry-agnostic compared to Buffett. Moreover, from time to time Ackman will also profit from more sophisticated trading techniques that involve derivatives.

One philosophy that Buffett and Ackman do share, however, is their love for value stocks. Neither investor is known for chasing momentum or overpaying for a stock trading with a lofty valuation.

The chart above benchmarks Amazon's price action relative to other megacap AI and cloud computing stocks. While each stock above faced some pressure earlier this year, Amazon's decline was more pronounced relative to its peers -- specifically throughout April. This is when Ackman pounced, buying the dip in Amazon stock during a period of notable valuation contraction.