Definition of 'Piggyback Mortgage'
A type of mortgage where a second mortgage or home equity loan is taken out by a borrower at the same time the first mortgage is started or refinanced. Piggyback mortgages are frequently used to lower the loan-to-value ratio (LTV) of a first position mortgage to under 80%, thereby eliminating the need for private mortgage insurance (PMI).
Investopedia explains 'Piggyback Mortgage'
Before using a piggyback mortgage to lower the loan to value ratio of the first mortgage to levels under 80% (to avoid PMI), a borrower should consider that a piggyback mortgage usually has a higher interest rate than a single, stand-alone first mortgage. If borrowers expect that their home will appreciate in value quickly (so that the LTV will not be higher than 80% for long), paying PMI for a period of time might be more economical than using a piggyback loan.
"80-10-10" is a common form of piggyback mortgage: where 80% of the property is covered by the first mortgage, 10% of the property's value is derived from the second loan and the final 10% is covered by the borrower's down payment.