San Francisco-based social games developer Zynga has set the estimated pricing range for its IPO, in an updated filing Friday with the SEC. Zynga said it estimates it will offer 100,000,000 shares of its common stock at between $8.50 and $10.00 a share. The IPO could be worth as much as $1.15 billion. Zynga has applied to list on the NASDAQ Global Select Market as ZNGA. Zynga's biggest investors are Institutional Venture Partners, Union Square Ventures, Foundry Venture Capital, and Avalon Ventures.