The power a Zestimate wields has unnerved some sellers. In January, a Cresskill, N.J., homeowner filed a lawsuit against Zillow, claiming the company selectively concealed Zestimates for some listings. The suit claimed that the company buried Zestimates for listings by brokerages that have a relationship with Zillow, while other listings had a Zestimate displayed prominently below the asking price. The arrangement amounted to an antitrust violation, the suit alleged.
The plaintiff’s home, an 18,000-square-foot, Spanish-style house, was listed last year for $7.788 million, but at the time, the Zestimate pegged it at $3.703 million. (The Zestimate for the house has since gone up.) Another nearby listing, by a large brokerage, showed no Zestimate beneath the price.
Ms. Heffter said that the company moves the Zestimate away from the list price when there is a significant disparity between the two, although she declined to say what threshold would trigger the change. Sellers cannot persuade Zillow to move or change the Zestimate, although they can update home details with new information, potentially changing the Zestimate.
“People disagree with their Zestimate all the time,” Ms. Heffter said. But altering the estimate whenever the list price is different would undermine the independence of the model, she said. “It’s something that needs to remain independent.”
However, without consistent information across comparable listings, the seller “is put at a competitive disadvantage,” said Edward Grossi, the lawyer for the homeowner, declining to give his client’s name.
Ms. Heffter declined to comment on the ongoing litigation. In a motion to dismiss the suit, lawyers for Zillow wrote that “it is unclear from the complaint how the placement of a Zestimate on a different property” would have any effect on the sale of the property.
List your home for sale, and a monthly curiosity can turn into a daily or even hourly obsession, particularly if you receive daily Zillow alerts on the status of your home, with fresh price estimates and details about how many people have viewed your listing.