I'm starting to understand now. BRK is worth $750B, which includes class A+B shares. His Apple stock, which they say is half of his stock portfolio, is worth $150B. So his entire stock portfolio is $300B. He also has $125B in cash.
So stocks and cash combined is $425B.
So the company is valued at $325B over and above its stock and cash holdings.
This is the result of investors bidding up the stock. We still have to figure out why they are bidding up the stock in the most recent quarter.
I don't think the performance of his stock portfolio was any cause for investor excitement. Remember that half of his stock portfolio (AAPL) crashed 10% this quarter. And another 30% of his portfolio (BAC, AXP, KHC, and KO) kind of languished overall, or perhaps went up a few percent.
So it must be BRK's private company portfolio that has been exciting investors and causing them to bid up the stock price. A couple of posters here have already alluded to this, but I'm finally catching on.
So let's take a look at BRK's private company portfolio, which was recently linked to [Thanks to Superstar2317 for this link]