Facebook

For the hordes of investors large and small who bought into hype around Facebook's IPO -- heck, even for those who snapped up shares two days ago -- this will offer little comfort. But in the last two days of trading, the assault on Facebook's stock has shaved a few billion dollars off the Facebook's famously rich founder's net worth.

More specifically, since the close of trading on Wednesday, Mark Zuckerberg has lost almost $3 billion, at least on paper. (His total stake is still worth about $11.8 billion, a far cry from the $19 billion he held at the IPO price).

As we all know, Facebook's stock has been struggling since its botched IPO on May 18. Ever since going public at $38 dollars a share -- and briefly reaching $45 on opening day -- it's been a bumpy ride down. The last two days have been particularly brutal. First, Zynga, which is tied at the virtual hip to Facebook, reported dreadful earnings, spooking Facebook investors. And then yesterday, Facebook reported its quarterly earnings, which left the Street unconvinced that company is moving fast enough to turn those 955 million users into big dollars.

Zuckerberg has sold some of his stock, which the company said was necessary for him to pay his taxes. Regardless of the reason, just after the IPO, he took some profits at a price that others would envy. He sold 30.2 million shares at $37.58 a share, netting him more than $1.1 billion.

As for the future, who knows. This is the stock market, after all, and past performance is no guide for future performance. Yet there are some key dates that Wall Street is worried about. Those are when the so-called lockup periods expire and more insiders can sell their shares, which doesn't seem so far-fetched for those who got them at, say, $1 a share.

One of those dates comes on August 15, when, 90 days after the IPO, 268 million shares held by stockholders other than Zuckerberg become available for sale. But the date that causes the most concern is November 13, when 1.24 billion shares will become available for sale.

It's well understood -- and Zuck and his team said as much on yesterday's conference call -- that Zuckerberg isn't going to cater to the short-term interests of Wall Street. So he might not care that much about the following painful stock chart: