Warren Buffett Just Revealed He Personally Chose Berkshire's Newest Mega-Stock. Here's Why That Changes Everything.

Most people who live to age 95 retired decades earlier. So when Warren Buffett announced last year that he planned to step down as CEO of Berkshire Hathaway (NYSE: BRKA) (NYSE: BRKB), some assumed that he wouldn't be very active in the company after the transition. After all, he was turning Berkshire over to a capable executive, Greg Abel, whom he respected and trusted.

Many (including me) thought that Abel was the key force behind Berkshire significantly boosting its stake in Google parent Alphabet (NASDAQ: GOOG) (NASDAQ: GOOGL) in the first half of this year. But Buffett recently revealed that he personally made the decision. Here's why that changes everything for Berkshire Hathaway shareholders.

Image source: The Motley Fool.

Correcting a past mistake

Buffett told Berkshire Hathaway shareholders at their annual meeting in 2017 that he made a mistake by not investing in Google years earlier. On the Monday following that meeting, the legendary investor stated in an interview with CNBC that he should have appreciated the strength of the company's advertising business because Berkshire's GEICO business spent a lot of money on Google ads.

In the months before he passed the baton as CEO to Abel, Buffett corrected his past mistake. Berkshire initiated a new position in Alphabet in the third quarter of 2025, buying around 17.8 million shares.

But that was just the beginning. In the first quarter of this year, Berkshire more than doubled its stake in Alphabet. On June 1, 2026, Alphabet announced that Berkshire had agreed to invest another $10 billion in a private placement.

As I mentioned earlier, many observers assumed that Abel orchestrated the move and was repositioning Berkshire's portfolio to be more tech-oriented. However, when CNBC's Becky Quick asked Buffett last week about the big investments in Alphabet this year, he replied, "I initiated it."

Why it's such a big deal

Is it an exaggeration to say that Buffett's personal involvement in spearheading Berkshire's big investment in Alphabet changes everything? I don't think so -- at least, not for Berkshire shareholders.

Most importantly, recent transactions confirm that one of the greatest investors of all time remains actively engaged in deploying Berkshire's massive capital. If this isn't reassuring to Berkshire shareholders, it should be.

If Buffett were only going into the office each day and making small investments, I wouldn't think much of it. However, Alphabet is now the fifth-largest holding in Berkshire's portfolio. Buffett isn't merely involved in small transactions; he's masterminding huge ones.

Granted, Buffett acknowledged that he wasn't "doing anything that he [Abel] doesn't approve of." Interestingly, though, he also said that Abel wasn't "doing anything I don't approve of." While Buffett quickly stated that Abel "is the decider," his comments underscore that Berkshire isn't in the "post-Buffett era" that some might have expected after he stepped down as CEO.

Should you buy Alphabet stock, too?

No one should buy shares of Alphabet solely because a famous investor did, even if that famous investor is the "Oracle of Omaha." It's also important to note that Buffett doesn't view Alphabet as his favorite stock. He told CNBC, "I would say that I don't like it as well as at least four or five other businesses that we own."

But Buffett also said in the CNBC interview last week that Alphabet is "more likely to be a winner" than 90% to 95% of the stocks that Wall Street favors. I suspect he's right (as he usually is).

In my view, Alphabet stands as one of the best-positioned companies to profit from nearly every aspect of the artificial intelligence (AI) revolution. Google Cloud is the fastest-growing of the top AI cloud service providers. Google Gemini consistently ranks among the most powerful AI models. Alphabet is integrating AI throughout its products, including Google Search. The company's Waymo unit is the leader in autonomous ride-hailing (robotaxis).

Buffett told CNBC's Quick, "It's not a question of whether it [Alphabet] was wonderful yesterday. It's the question, 'How long is it going to be wonderful?'" Berkshire has bet over $30 billion that the answer to that question is "probably a long time." I believe that's the correct answer.

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.