Factbox - Facebook's IPO: who gets rich?

SAN FRANCISCO (Reuters) - 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 (3.46 billion pounds) -- of the roughly $10.6 billion it plans to raise via a mega IPO. The other half, or about $4.9 billon, 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.

Assuming the mid-point price of $31.50, following are details on the amount the selling stockholders will make:

* Accel Partners $1.2 billion

Accel Partners $1.13 billion

Lead investor Jim Breyer $72.75 million

* Mark Zuckerberg $951.3 million

* Digital Sky Technologies $827 million

* Goldman Sachs $415 million

* MAIL.RU $355 million

* Peter Thiel and associated funds $244 million

* Meritech Capital $220 million

* Greylock Partners $220 million

* Microsoft Corp $207 million

* Elevation Partners $145 million

* Tiger Global Management $106 million

* Mark Pincus $31.8 million

Mark Pincus Personal $22.66 million

Ogden, an entity controlled by Pincus $9.13 million

* Reid Hoffman $29.7 million

Aufklarung, Hoffman's angel fund $24.7 million

Reid Hoffman $2.5 million

Michelle Yee, Hoffman's wife $2.5 million

(Reporting By Poornima Gupta and Gerry Shih; Editing by Bernard Orr)