Group coupon site Groupon announced its plans for a $750 million initial public offering last week, but the Chicago-based company’s IPO filing contained some disquieting information about its finances.

Among the information was the company’s uneven rate of cash flow. Revenue growth went from $3.3 million in the second quarter of 2009 to $644.7 million in the first quarter of 2011. But “free cash flow” in 2010 was said to be just $72.2 million, including $7.0 million in one quarter despite revenues of $644.7 million.

The company’s accounting has been termed, “Grouponistically Acclaimed Accounting Procedures” by the Daily Deal. Writer Don Young Jr. noted that the company's net loss last year was $413.4 million, and in the first quarter of this year was $113.9 million, giving it an estimated burn rate of nearly $450 million a year. That's a whole lot of coupons.

The Financial Times noted that the company spent much of its earlier $1.1 billion in financing on enriching its founders, and that its marketing, administration and sales expenses rose from $11 million in the first quarter of 2010 to $387 million in the first quarter of this year. To measure its profitability, the company uses something called "adjusted consolidated segment operating income," or "adjusted CSOI," which leaves out the expenses of acquisitions such as buying CitySearch in Europe and for online marketing. It's not clear if adjusted CSOI is something that's going to catch on anytime soon with the accounting standard-setters at FASB.