piggyback mortgage means: Homeowners use piggybacking to lower their loan-to value ratio and get rid of private mortgage insurance PMI. A homeowner can either take out two mortgages at once or one mortgage with piggybacking. Splitting the total amount of the mortgage into two loans allows the borrower to reduce the ratio between the mortgage amount and the property’s value to less than 80. This is the floor for PMI. This method has a downside: the interest rates on the second mortgage are usually higher than those of the original mortgage. You can also use piggybacking on some types of loans. (in Stock Market Dictionary)