I thought that was assumed? Of course no billionaire has the money sitting in a bank account or in a swimming pool of gold coins. Fortune doesn't imply cash money.

this is how all wealthy people have their net worth reported - not sure why you’re so adamant that “net worth” only include cash for some reason when it’s a completely accepted fact that net worth is the sum of your assets minus debt.

I like this reasonning, but otoh nobody has a lot of money in cash. When you count somebody’s fortune, you must also count assets that may produce different valuation when sold.

It's an unrealized asset. It can be included as a footnote on his personal net worth but isn't part of it until it's sold. For a founder, the red-tape involved in selling stock is significant and they must wait for the market to absorb the announcement of their intention to sell. I recall when Bill Gates sold something like $200M of his stock to pay for his lake-side mansion and that the SEC filing went out of the way to express that Gates didn't really want to sell anything but it was the only way he could finance his new mansion... in other words, there's no insider knowledge about Microsoft that prompted his selling. For Zuck to cash out he would have to announce well in advance and then say he's going to sell X percent every first trading day of the month (or whatever period he defines) whether the stock is going up or down in order for it to not be taken as an insider move.

(In fact, selling covertly or converting stock to any financial instrument covertly -- what's called "buying a collar" -- is quite illegal and will land you in jail if caught.)

You are quite naive. These people don't have to sell their stocks in order to finance something like building a house. They get massive loans using their stocks at collateral.

Some of Larry Ellison's emails with his financial advisor became public and talk about doing just this.

It is common practice for nearly all those wealthy people relying on stocks. What I am interested in is the interest rate they get on those loans.

It's actually lower than retail bank interest rates. For example, if they get a huge mortgage, usually it is at least 100 basis points lower. This is because these people are considered extremely low risk.

I have heard it is pretty common for them to get 1 or 2% because the banks usually want to win their business.

It's also worth noting that Zuck has the sort of holding FB that to actually liquidate it would involve either an institutional investor, or a massive drop in the stock price. He owns 30% of FB (and has more voting rights), any significant liquidation would involve a drop in value. People VWAP far less.

And if he did cash them all out, he'd crash the price

Sadly, this must be the easiest article for Bloomberg to write. They'll write another when his net worth dips below $100B.