It's relevant to link to Citron Research's scathing report that Zillow is among the most egregiously overvalued public tech companies, with large insider selling and video footage from management admitting to its partners that it does not have profits with which to pay them.
Keep in mind that Citron Research is known for providing info for short-sellers. So it's somewhat in their interest to see the stock go down for companies they review and, in turn, suggest their readers short.
Note: they've recently been doing lots of reviews on Z
Largely true, but they've also put out Long reports, namely Blackberry recently which they highlighted about a year ago and have reiterated their positive stance, which has played out in the market. I add this not to toot their own but even out the message that although they're known for their shorts, that's not all they research and pick.
http://www.citronresearch.com/wp-content/uploads/2013/09/zil...