According to the wall street journal Overstock had this program where they encouraged university students to put links back to them which as a result they'll receive discounts for items on Overstock. As we are all aware links from universities means .edu links and boy they "count" like sky high in search engines point of view.
Although it is questionable what the most of universities "reveling" these days but the rest assured from the Google's point of view they are very trustworthy links. Recently they used to rank pretty high for keyword such as "vacuum cleaners" or "area rugs", etc which brigs a lot of traffic thus they convert them to $$ but ultimately their greed paid the ultimate price for it.
Now if you search for "area rugs" for instance their site is located around 6 th SERP. And according to them now after the slap they've decided to cancel that "program" and said that hope Google will bring them back. Don't know about you guys but um... usually even though Google slaps someone but if they're like the "big" guys in the game after correcting the issue they'll be brought back to "life" as the case with BMW slap which happened few years ago.