Online daily-deals originator Groupon was prepared Friday morning to debut as a public company, offering stock that would value the Chicago company at a total seen only once before in history for a technology company’s initial public offering.

Groupon filed Thursday to sell 35 million shares — about 5.5 percent of the company, a smaller percentage than is normally offered — at $20 apiece. That would set the company’s market value at $12.7 billion, the second-highest total in tech history to Mountain View Internet giant Google (GOOG), which had a valuation of $23.1 billion when it went public in 2004.

The initial offering of Groupon’s shares were expected to begin trading on the Nasdaq composite index, under the ticker symbol GRPN, at 10:40 a.m. in New York.

One of the most anticipated and hotly debated initial public offerings of the year, Groupon’s performance could help grease the skids for other Internet firms — and especially social media companies — that have been waiting to go public amid an extended market slump.

As the second of the “big five” social media companies to go public — after LinkedIn — Groupon could reignite investor interest in consumer Internet companies and pave the way to new riches for valley tech executives and venture capitalists. Zynga is expected to follow suit later this month and Facebook early next year, with Twitter probably waiting until 2013.

Groupon began offering daily deals to subscribers in 2008, when founder and CEO Andrew Mason figured out how to use the Internet to crowd-source deals at local merchants. Customers receive daily emails offering a chance to buy discount deals for a range of services and goods, such as meals, massages and backpacks, as long as enough people sign up for the deal. The company then takes a cut of what people pay and gives the rest to the merchant.

The IPO would bring the reportedly cash-poor company $700 million. In July, Groupon had to shelve plans for a $750 million IPO after the Securities & Exchange Commission raised concerns about its accounting practices. The company was forced to dramatically restate its revenues — from $713 million last year to $313 million.

In an updated SEC filing late last month, Groupon said it had narrowed its third-quarter losses to $1.7 million. That was a marked reversal from the first six months of the year, during which the company lost $255 million on revenue of $1.52 billion.

The company now has nearly 143 million subscribers for its daily deals, according to the latest filing, a sevenfold increase from last year. But it is making significantly less revenue per subscriber than earlier this year. After starting in Chicago, it has expanded to 175 markets in North America as well as 45 other countries. Despite its rapid growth, net revenue grew only 10 percent last quarter, compared with more than 112 percent for the year-earlier period.

Observers have worried about the rate at which the company is burning cash to acquire new customers. In the first nine months of this year, Groupon said, it spent $613 million on marketing, compared with less than $90 million in the same period of 2010.

Earlier this year, the company announced that it had closed an eye-popping $950 million funding round from some of the tech industry’s leading investment firms. The vast majority, though, went not into the company’s coffers but to buy out shares held by its co-founders and early investors — whom many critics assailed for pocketing money the company needed to sustain its growth.

Perhaps mindful of that criticism, Groupon insiders did not sell any additional shares of their stock Friday, meaning they will have to wait until after the SEC’s six-month “lockup” period to reap any gains from the IPO.

NEA and Accel, the largest local shareholders of Groupon, appear to be in decent shape — for now, anyway. At the $20 price, NEA’s stake in the company would be worth about $1.8 billion, while Accel’s would tally almost $1 billion. According to estimates by the National Venture Capital Association and Thomson Reuters, the two firms have put $160 million and $170 million, respectively, into Groupon.

It’s less clear what will become of the stakes held by other Silicon Valley venture firms that pumped hundreds of millions into the company in two funding rounds this year. They range from venerable blue-chips Greylock Partners and Kleiner Perkins Caufield & Byers to hotshot newcomers Andreessen Horowitz. (Others who’ve invested heavily in Groupon include Starbucks CEO Howard Schultz, AOL vice chairman Ted Leonsis, Menlo Park private equity giant Silver Lake and Russian investment powerhouse Digital Sky Technologies.)

While it’s unclear what those investors believed the company to be worth in the spring, Groupon when it first filed to go public was talking openly of a $30 billion valuation. At the midpoint of the new price range, it would have a market value of just under $11 billion

Vivek Wadhwa, an entrepreneurship expert at Duke University who’s been an outspoken critic of Groupon’s IPO plans, said he expects the stock would see a big first-day jump.

“This is being orchestrated by the investment bankers,” he said. “They are selling this deal aggressively despite its apparent flaws. My fear is that the people on the inside start selling soon after and the stock drops dramatically after a few months.”

“A successful IPO will be good for the tech industry, but a drop in stock price will be a disaster,” he added. “The public gets burned and shies away from future offerings.”