Zillow Inc., which operates the real estate site Zillow.com, Zillow Mortgage Marketplace and Zillow Mobile, finished day one of trading on the the Nasdaq Global Market as shares closed at $36.14, up 81 percent. The compnay initially announced the pricing of the initial public offering (IPO) of 3,462,000 shares of its Class A common stock at $20 per share, as shares began trading on Wednesday under the ticker symbol "Z." The underwriters have a 30-day option to purchase up to an additional 519,300 shares of Class A common stock, to cover over-allotments, if any. All of the shares of Class A common stock are being offered by Zillow. Concurrent with the completion of the initial public offering, Zillow will complete a private placement of 274,999 shares of its Class A common stock, at $20 per share, to certain existing investors in Zillow. Zillow's earnings come from real estate and mortgage professionals as well as advertising. In mid-April, Ellie Mae hit the market at $6 per share, hit a high of $7.30, and is currently trading back down at $6.