Today’s business term is “high ratio mortgage”. A high ratio mortgage is a mortgage of over 80% of the value of the property being mortgaged. Put in other words, it is when the borrower is putting down 20% or less, as a down payment. Often, the borrower is going to have difficulty getting such a loan without having Private Mortgage Insurance (PMI). PMI allows the borrower to buy a property with as little as a 3%-5% down payment (source). The amount that the borrower has to pay per month for PMI is dependent on the how much is left on the mortgage.