Billionaires Warren Buffett, Stanley Druckenmiller, and Izzy Englander Loaded Up on This Quantum Computing Stock. Should You Buy It Too?

If you follow billionaire investors, you'll quickly find that they don't always see eye-to-eye. Their portfolios reveal significantly different investment styles. However, the ultra-wealthy investors sometimes agree on the potential of the same stock.

That was the case in the third quarter of 2025. Billionaires Warren Buffett, Stanley Druckenmiller, and Israel "Izzy" Englander loaded up on the same quantum computing stock.

Image source: Getty Images.

Billionaires' quantum entanglement

You probably won't be surprised that Buffett, Druckenmiller, and Englander didn't all decide to scoop up shares of a small, unprofitable pure play focusing on quantum computing. Instead, the three investors each added shares of a tech giant that's a leader in quantum computing – Alphabet (NASDAQ: GOOG) (NASDAQ: GOOGL).

Buffett is perhaps the most surprising buyer of Alphabet in Q3. The "Oracle of Omaha" stated several years ago that he regretted not buying shares of Google's parent company earlier. However, he didn't correct that mistake until a few months before his retirement as CEO of Berkshire Hathaway (NYSE: BRK.A) (NYSE: BRK.B). Buffett either approved of or directly initiated the purchase of a $4.3 billion stake in Alphabet.

Druckenmiller's Duquesne Family Office didn't own a position in Alphabet immediately before Q3, either. However, the billionaire purchased 167,900 shares of the company last quarter.

Englander's Millennium Management hedge fund already had stakes in both share classes of Alphabet going into Q3. Millennium Management increased its position in Alphabet Class A shares by 65.5% in the quarter and in Alphabet Class C shares by 33.5%.

Why Buffett, Druckenmiller, and Englander are buying Alphabet

Alphabet's Google Quantum AI has achieved two notable milestones in quantum computing. In 2019, the unit went beyond classical computing by using a quantum processor to perform a calculation in only 200 seconds that it said "would have taken the best-known algorithms in the most powerful supercomputers at the time 10,000 years to accomplish." In 2023, Google Quantum AI demonstrated a practical form of quantum error correction with a logical qubit prototype.

Did Buffett, Druckenmiller, and Englander buy Alphabet stock hand over fist because of the company's tremendous quantum computing potential? Probably not. Instead, I'd bet the farm that these famous investors focused much more heavily on Alphabet's advertising juggernaut and its artificial intelligence (AI) opportunities.

While Alphabet generates revenue in many ways these days, advertising remains its top moneymaker by far. In Q3, the company raked in a whopping $102.3 billion in revenue. Over 72% of that total stemmed from advertising on Google Search, YouTube, and other platforms.

Alphabet's AI opportunities are at least partially tied to its advertising business. For example, the company is using AI to help advertisers boost conversion rates. Google Search integrated generative AI with its AI Overviews and AI Mode features, moves that management says are driving higher query volumes (which means more eyeballs for advertisers to target).

However, the bigger AI prize for Alphabet is Google Cloud. CEO Sundar Pichai stated during the company's Q3 earnings call that more than 70% of Google Cloud's existing customers now use its AI tools. Revenue from the cloud provider's AI products more than tripled year-over-year in Q3.

Should you buy Alphabet stock too?

I'd never advise anyone to buy a stock solely because billionaire investors bought it. Their objectives and risk tolerance could be quite different than yours. That said, I think Alphabet is a great stock for many investors to consider buying.

The company's advertising business appears to be rock-solid. Previous worries that generative AI would be the technology that toppled Google Search now seem unfounded. GenAI has turned out to be a catalyst for Alphabet's search engine.

I believe Alphabet can continue to grow tremendously for years to come due to the demand for AI. In particular, my view is that agentic AI will provide a major tailwind for Google Cloud and the Google Workspace productivity suite.

Last, but not least, I think that Alphabet has a couple of wild cards up its sleeve that could pay off big-time over the next decade and beyond. One is its Waymo autonomous ride-hailing business. What's the other? Quantum computing.

Keith Speights has positions in Alphabet and Berkshire Hathaway. The Motley Fool has positions in and recommends Alphabet and Berkshire Hathaway. The Motley Fool has a disclosure policy.