Chances are shorts figured out that Clearwire is selling their shelf shares at $1.20 when Sprint issued their report on their own holdings and said that they did not know their actual share count yet because Clearwire,s offering is still ongoing.
So shorts figured a $1.20 ceiling for now gives them room to short it down.
And then add in that shares of CLWR are massively oversold right now, but there appears to be no new buyers of the stock at these levels. If I had more ca$h, I'd be backing up the truck at these prices. The problem is that there's not too many people out there who agree, apparently.