How Much Will Facebook Investors Make From IPO?

The rich are going to get richer when Silicon Valley's biggest IPO starts trading.

Facebook

is only getting about half — or $5.6 billion — of the roughly $10.6 billion it plans to raise via a mega IPO. The other half, or about $4.9 billion, is going to a handful of inside investors — many Silicon Valley notables.

Chief among them are co-founder and Chief Executive Mark Zuckerberg, venture firm Accel Partners, early investor and PayPal co-founder Peter Thiel, Russian tycoon Yuri Milner's DST, and investment bank Goldman Sachs.

And Mark Pincus, co-founder of the gaming company Zynga, is set to get his second payout in six months. He stands to make almost $32 million, on top of his take when the social gaming giant he co-founded went public last year.

Those holding onto their stakes — for now — include: Napster co-founder and Facebook founding president Sean Parker; co-founder and Zuckerberg's Harvard roommate, Dustin Moskovitz; various Facebook executives; and venture capital firm Andreessen Horowitz.

The largest seller is Accel Partners, which will make about $1.2 billion if the shares sell at the $31.50 mid-point of an indicative price range. Zuckerberg, who started Facebook in 2004 from his Harvard dorm room, is selling the next largest chunk of shares worth a little under $1 billion.