It will drop when that happens, but it would probably not make sense to make that bet.
If you can construct a portfolio that exposes you to only that specific event (and not something like the further increases in value until that point -- seems difficult but maybe possible?) you might learn the probability of it happening at various points in time, through its price!
Maybe you'll find that portfolio seriously underpriced (another comment gave some potential reasons why it would be) in which case there's money to be made.
> If you can construct a portfolio that exposes you to only that specific event (and not something like the further increases in value until that point -- seems difficult but maybe possible?)
You'd do that by going long in all stocks that Berkshire owns, and short Berkshire itself. The problem with that is that Berkshire also has a bunch of non-listed subsidiaries you can't buy.
If you can construct a portfolio that exposes you to only that specific event (and not something like the further increases in value until that point -- seems difficult but maybe possible?) you might learn the probability of it happening at various points in time, through its price!
Maybe you'll find that portfolio seriously underpriced (another comment gave some potential reasons why it would be) in which case there's money to be made.