I bought my 2 bedroom coop 2 years ago. Since then while the housing prices around me have risen significantly (the same exact units on the floors both above and below me both sold recently at much higher prices), Zillow has been regularly sending me notifications that the value of my home has dropped. Zillow now values it about a third of what I paid for it, and about one-fifth of to one-quarter of what similar units in my building and in my neighborhood have sold for.