What did he do so he owes taxes?
Exercising in-the-money options is taxable. Receiving stock grants is a taxable event.
Owning stock (or options) in a company that goes public is not a taxable event.
Note that he got to sell (some?) now. Ordinary employees are still in lockout.
EDIT: The lock-up period isn't an SEC requirement; it's an agreement made with the underwriters. The S-1 filing states:
"Morgan Stanley & Co. LLC may, in its sole discretion, permit our executive officers, our directors, and the selling stockholders to sell shares prior to the expiration of the restrictive provisions contained in the “lock-up” agreements with the underwriters."
And it looks like they let him do just that.
Let's say he exercised options that earned him $5BB. (I don't know what the exact amount was. It was in the billions, no doubt.) So let's say maybe he owes $2BB in taxes. As for the rest of his shares and what they are "worth", those are going to fluctuate in value, based on the company's performance.
Now, let's say you are a FB shareholder. Ask yourself as a shareholder if the FB CEO has earned a $5BB salary. What has he done for you? How is your FB stock doing? OK, so let's say you think he is a genius and certainly deserves $5BB. Then ask yourself why he would want $5BB in income in _one year_. He wants it all right now. That's an awful lot of income. And a lot of tax to pay.
Why the rush to cash out?
Whatever happens to Facebook, he is set for life. Good for him, but not necessarily good for Facebook shareholders. He has little incentive to deliver.
Wall St. is going to love him, I can already tell.
MM is semi-standard English, at least in the US, because M can be confused with the M used for one thousand.
But B doesn't get confused with anything, and I've never seen BB written anywhere before this..
If FB revenues continue to go up, then I'm wrong. But unless Facebook "finds" a novel business model I do not see revenue continuing to climb; I believe we are at the peak, and now begins the descent. If he waited eight years, then why not wait a little longer? I believe there is a reason now was the time. Time will tell.