Despite warnings from Wall Street analysts, the public offering of the online coupon outfit Groupon raised $700 million.

This is the largest IPO by an Internet company since Google raised $1.7 billion in 2004. It means that Groupon is apparently now valued at almost $13 billion after increasings the offering by 5 million shares to 35 million in total and pricing them at $20 each, above an initial range of $16 to $18. The three-year-old company, which sells Internet coupons for everything from spa treatments to nose jobs, is one of this year's most closely watched. It has only floated five percent of the company and helped drive up demand and price.

However analysts have been warning that the outfit could face long term problems including competition from the deep-pocketed likes of Google and Amazon. It will need to spend continuously to drive user growth.  There were also questions about accounting after the company altered its IPO filings twice to change the way it accounted for revenue. There are also concerns about the company's ability to generate long-term profit and revenue growth, plus the likelihood that existing investors will flog some of their holdings at some point.