A heavy financial load brings us this week's Marketplace Money buzzword: Piggyback.

A piggyback is a type of mortgage loan. It's used by homebuyers who can't afford the downpayment on a house. Instead of taking out just one mortgage, they piggyback a second one on top of it.

People with good credit can shoulder a piggyback, but some borrowers with bad credit . . . can't. Lots of them are defaulting on piggybacks they probably shouldn't have been offered at all. This week, Fremont General, a big lender to risky borrowers, stopped offering piggybacks. All those defaults kept the company from bringing home the bacon.