The Regret That Cost Buffett Trillions: Why He Never Bought Microsoft

The Setup: Warren Buffett is arguably the best stock picker alive. Yet even legends have their blind spots—and Microsoft might be his most expensive one.

The Real Story Behind the Miss

Here’s the thing: Buffett loved Microsoft’s business model. He publicly praised the company for decades. So why didn’t Berkshire Hathaway ever pull the trigger?

The answer reveals something uncomfortable about even the greatest investors: personal relationships can override rational decision-making.

Buffett’s friendship with Bill Gates, Microsoft’s co-founder, created an invisible wall. At Berkshire’s 2018 shareholder meeting, Buffett flat-out said it: “It would be a mistake for Berkshire to buy Microsoft.” Not because the company was bad—because investing might look like favoritism. Worse, regulators could question whether Buffett had access to non-public information.

Translation: Integrity beat greed. But greed would’ve paid better.

The Cost of Sitting Out

Let’s do the math:

• Microsoft’s market cap: $3.5 trillion (up 780% over the past decade)
• Current ranking: World’s 4th most profitable public company
• If Buffett had bought $1B in MSFT a decade ago: He’d be sitting on roughly $8B today

That’s not chump change—even for a guy worth $700B+.

Why This Matters Beyond Buffett’s Portfolio

This story actually reveals a fundamental tension in investing:

The paradox: Microsoft checks every single box on Buffett’s investment checklist:

• Strong competitive moat (software network effects)
• Consistent revenue streams
• Disciplined capital allocation
• Leadership depth
• Long runway for growth

Yet personal considerations kept him out. It’s a reminder that even systematic investors can let non-financial factors derail billion-dollar decisions.

The Broader Lesson

This isn’t about Microsoft specifically. It’s about recognizing when we’re using plausible excuses to avoid something. Buffett could’ve found workarounds—selling to Berkshire subsidiaries, disclosure arrangements, etc. Instead, he chose constraint over capital.

Sometimes that’s wisdom. Sometimes it’s just expensive.