“-- Continuing to clear the decks for new leadership. The extent to which Mr. Buffett has already passed the operational baton to Mr. Abel was clearer to me at this year's annual meeting than it had been before. Perhaps he is doing the same with the investment portfolio.”

If we are allowed to speculate about factors, a possible extension of the above could be that Greg has made clear that once he is in charge he will likely be more trigger happy on the sell button for some of the large positions. After all the corporate culture seems to support “clean slate” approach, CEO is chief risk officer and all that (see e.g full liquidation of Mr Simpson portfolio). On the one hand it would be uncharacteristic of Mr Buffett to sell ahead of this, but on the other hand the knowledge that the position is likely to be sold in future could make it a rational decision to sell ahead of that future. Especially if that future is fast approaching and valuation and tax considerations support it on the margin.