This is the latest news on the real worth of Mark Zuckerberg when taking into account the real money raised by Facebook's IPO and Zuckerberg's stake in the company. If you consider the $16 billion raised in the initial IPO, and the fact that Zuckerberg owns 28% of those shares, you get an estimation of about $4.5 billion dollars. If he sold all of his shares, and others bought them at current trading value, he would have $4.5 billion cash in hand. Or "in vault" as the case may be.
Obviously, this isn't going to happen. Zuckerberg as CEO - selling all of his shares would not be a good thing. If the founder and CEO were to sell his shares at the beginning of the IPO, all confidence would be lost and stocks would plummet. If he could even find someone to buy them, without raising a bunch of eyebrows.
Instead, what this is, is a more realist interpretation of the kind of buying power Zuckerberg now has. Some estimates put his worth at around $28 billion, representing his 28% stake in the companies $100 billion valuation. But in terms of buying power, this $4.5 billion estimate is much more accurate. If Zuckerberg now chooses, he has a lot of options for personal investments.
If it were me, I'd take out enough to buy a personal island. That's the only way you can get away from Facebook these days.
source: click here for a large version of the infographic at Visual.ly