Year: 2010

Buyout offer: $6 billion from Google

What happened: Groupon was the darling of the tech world two years ago when Google offered to purchase the group-buying web service for $5.3 billion with a $700 million earn out. The Chicago-based company decided it could do better on its own and turned down deal that would make its three co-founders instant billionaires. A year later Groupon raised $700 million during its intitial public offering which raised the company's valuation to $12.8 billion.