Facebook  will offer 180,000,000 shares of its common stock for an initial public offering price of $28 to $35 a share, the company announced Thursday via amendments to its S-1 filing . Class A shares will bring in between $5 billion and $6.3 billion for Facebook, and existing shareholders will sell an additional 157,415,352 shares. The company's total valuation is between $77 billion and as high as $96 billion. Mark Zuckerberg's roughly 57% stake in the company is valued as high as $18.7 billion. Trading is expected to begin May 18.