из статьи, ссылку на которую раньше давал "An underwater mortgage is a mortgage where the homeowner owes more to the lender than what the home is worth. This can happen when the homeowner’s property value depreciates after purchasing the property.
When this happens, the homeowner might not have any equity in the home. This can negatively affect a person’s available credit and prevent the borrower from refinancing the mortgage. The homeowner may not even be able to sell the home without putting in their own cash to cover the losses. " . как часто такое бывает, идут ли банки навстречу - понятия не имею. у меня нет ипотеки и в ближайшие месяцы не планирую