When Facebook launched it’s IPO on Friday, CEO Mark Zuckerberg contributed 30.2 million of his own shares in the company to the sale. Those shares, as it turns out, sold for $37.58 each, netting Zuckerberg a cool $1.1 billion dollars.

Unfortunately, however, Zuckerberg doesn’t get to do a Scrooge McDuck impression and go swimming in all that money. According to the LA Times, the bulk of that money will go to filling Uncle Sam’s money bin in the form of taxes. Zuckerberg, however, still has another 503.6 million shares of the company, meaning that he’s still worth billions of dollars

Just how many billions of dollars those shares are worth, though, has fluctuated wildly over the past few days. Shortly after opening on Friday, Facebook’s stock price briefly shot up to $42 per share, a significant jump over its $38 per share IPO price. Since then, however, the stock has mostly been on a downward slide, and is currently trading at $31.88 per share (though that’s 2.84% higher than its opening price this morning).

At the current price, Zuckerberg’s remaining shares are worth a little over $16 billion. Facebook’s market cap, meanwhile, is sitting at $68.14 billion. Facebook’s IPO has performed poorly thus far to say the least, and with the controversy brewing surrounding Morgan Stanley’s revised revenue report, it may be a long while before the stock shows much gain.