Even when a seller and buyer agree on a price for a home, the deal can collapse if the property appraises for less than that price.
For example, let's say a seller lists his house for $325,000, the buyer offers $275,000, but they settle on $300,000. A week before closing, the appraisal comes in at $265,000. That's the maximum price for which the lender is willing to offer a mortgage.
Who's going to make up the $35,000 difference?
In this case, the seller has already come down on the price and doesn't want to lower it again. And the buyer may not have enough cash to cover the shortfall, or does not want to pay more for the house than its appraised value.
As a result, the deal falls through.