Subject: Re: The S&P 500’s Yield Is Weak.
the point is the stock was a great value 15-20 years ago, he didn't swing

We typically say that Berkshire will buy back stock when it is below a certain value. And that's generally true. But I would argue that there is an additional implicit condition that has to exist at the same time - that they believe there aren't OTHER more promising investments appearing on the near horizon!

Maybe 15-20 years ago, Buffett believed that even though Berkshire stock was a good value, he could find BETTER investments out there for the cash to be deployed into.