The filing did not identify buyers, but indicates Groupon intends to raise a total of $900 million. The company has been entering three to five new U.S. markets a week with its service, which negotiates group discounts of 40-70% with retailers, restaurants and other businesses and posts them on its website. If enough people sign up for the deal, it activates. The service will also sell its daily deals via e-mail or post them to subscribers Facebook accounts.
    The model harnesses social networking by providing consumers an incentive to spread the word virally with their freinds to ensure enough people sign up to activate the deal. It is being watched closely by specialty retailers and marketers because it harnesses the web to send traffic to local brick-and-mortar businesses rather than online retailers.
    Earlier this month Groupon spurned an unsolicited offer by Google to buy the private company for $6 billion. The company is expected to pursue an initial public offering.