It's not surprising that Zillow's AVM [1] isn't accurate for this sale. The model needs local comparable sales data to function properly which it didn't have in

It's not surprising that Zillow's AVM [1] isn't accurate for this sale. The model needs local comparable sales data to function properly which it didn't have in this case; it's not everyday that mansions are bought and sold. The next best thing it can do is look at the last recorded sale (or tax assessor's indication of value) and project out by looking at market trends and applying some other proprietary mumbo-jumbo to come up with a price. [1]: https://en.wikipedia.org/wiki/Automated_valuation_model https://en.wikipedia.org/wiki/Automated_valuation_model