Warren Buffett Bets Big on AI -- He Just Bought 17,846,142 Shares of This Legendary Tech Stock

Warren Buffett is stepping down as head of Berkshire Hathaway (NYSE: BRK.A)(NYSE: BRK.B) at the end of 2025. But for now, no portfolio transaction occurs without his blessing. That's what makes Berkshire's recent trades so interesting. According to recent filings, Berkshire just acquired 17,846,142 shares of a popular artificial intelligence (AI) stock -- a category Buffett has long avoided.

After the purchase, Berkshire owns $4.3 billion of this AI company, pushing it into its top 10 holdings by value. Why is Buffett suddenly going all in on artificial intelligence? There's more to this story than you might expect.

Buffett owns more AI stocks than you think

Historically, Buffett isn't a huge fan of tech stocks. But in recent years, tech stocks have been some of his biggest holdings.

Just look at Berkshire's top position right now: Apple. That position alone is currently worth more than $60 billion. But in the past, this holding was worth more than $200 billion! A slew of selling has cut the position's weight significantly, yet Apple remains Berkshire's biggest bet. Apple isn't a stand-alone AI company. But the company has spent billions of dollars on AI research and development, rolling out several new AI tools to customers in 2025 alone.

Apple isn't the only company in Berkshire's portfolio that is involved in AI, either. Since the first quarter of 2019, Berkshire has also owned a multibillion-dollar position in Amazon. Most people know Amazon as an e-commerce platform, but most of its operating profits are actually generated by its cloud infrastructure business, Amazon Web Services (AWS). As the largest cloud provider in the world, AWS is used heavily by AI companies to train and run complex AI models.

Here's the catch. Buffett may not have been responsible for these purchases, even though he obviously approved them. According to most reports, the Apple purchase -- which quickly became Berkshire's biggest bet in history -- was actually initiated by two of Buffett's lieutenants: Todd Combs and Ted Weschler. The pair was also reportedly responsible for Berkshire's purchase of Amazon stock. "Yeah, I've been a fan, and I've been an idiot for not buying," Buffett said after Combs and Weschler finally convinced him to buy Amazon shares.

There's a strong chance that Combs and Weschler are also behind Berkshire's latest purchase: Alphabet (NASDAQ: GOOG)(NASDAQ: GOOGL), the parent company of Google.

Image source: Berkshire Hathaway.

Berkshire Hathaway is betting big on Alphabet stock

According to the latest SEC filings, Berkshire now owns 17,846,142 shares of Alphabet stock, the parent company of Google. This position was never declared in previous filings, strongly suggesting that Berkshire purchased all its shares during the third quarter of 2025.

As with Berkshire's Apple and Amazon positions, we don't know who initiated this purchase. As a recent report from Reuters concluded, "It is not clear whether Buffett, his portfolio managers Todd Combs and Ted Weschler, or CEO-designate Greg Abel make specific purchases, though Buffett normally makes larger investments."

I'm betting Buffett was at least partially involved. In the past, he and former partner Charlie Munger have lamented not buying shares of Alphabet earlier. "We screwed up," Munger once revealed. "He's saying we blew it," Buffett added.

While Google still makes most of its money from its search engine and advertising businesses, the company is also a major player in the cloud computing industry. Most estimates peg it as the third-largest cloud provider in the world, with a market share of 10% to 15%. Like Amazon's AWS division, Alphabet's cloud business is heavily used by AI developers and applications.

With this purchase, Berkshire now owns three companies with direct ties to AI. Buffett -- or, more likely, his investment partners at Berkshire -- seems to be increasingly bullish about AI's potential.

Ryan Vanzo has no position in any of the stocks mentioned. The Motley Fool has positions in and recommends Alphabet, Amazon, Apple, and Berkshire Hathaway. The Motley Fool has a disclosure policy.