What jumps out at me about this list is that, with one or two exceptions, they're not great businesses -- in the sense of having high and durable returns on capital. You can run a supermarket or a gas station diligently without much of the revenue ever making it to the bottom line. I bet Mr. Buffett would have liked to buy Mars. Who knows, maybe we will one day. I don't know much about Cargill, but I can't imagine it's that much better than, say, ADM or Bunge, which have pretty uninspiring margins.

There is one grocery chain I'd love to see Berkshire keep an eye on: Wegmans. I haven't lived in a state with a Wegmans for 16 years but I still miss it. I don't know anyone in Wegmans country who doesn't shop there. Whole Foods and Trader Joes barely made a dent in their market share. I don't know what their annual revenues are, maybe $15B.

As far as gas stations, Buc-ees seems to inspire similar loyalty. They're smaller, maybe $4-5B annual revenue -- very high mix of in-store sales compared to sales at the pump, which is where you want that ratio. Maverik has a lot of loyal customers here but it's probably not for sale to Berkshire at a price we'd want to pay. If FJ Management ever sells (to non-Mormons), I think they shop it to smaller PE firms and try to start a bidding war.