Analysts have recently pegged the company's value at $25bn. The share sale looks set to create a new set of dotcom millionaire and billionaires as Groupon's investors and early employees see their shareholdings turn into paper fortunes. Groupon's largest shareholder, Eric Lefkofsky, a co-founder and board member, owns 64.1m shares, 21.6% of the company's Class A common stock. Mason controls 7.7% of the company. The Groupon filing follows the sale of LinkedIn, the business network.