Subject: Re: A B spread 2.35%
"The only explanation that has come up is something obscure related to the rise of fractional share trading, but I really don't know."

To me, the slight economic premium for the A shares always represented the value in the extra voting rights inherent in the A shares. For a long time those extra voting rights were not worth much because Buffett and Munger had such a large, outsized influence in the company that shareholder votes really did not matter all that much.

As time has gone on, Buffett has slowly been disposing of his shares and more and more As are being converted into Bs. Now Munger is gone. The extra voting rights of the A shares are becoming more valuable.