Americans are raiding their already fragile retirement piggy banks to weather financial hardships such as unemployment, medical emergencies and buying a home. And they're doing it even though borrowing a modest $5,000 can dramatically erode savings over time, according to a study released July 15 by the Center for American Progress. The study found workers in 2004 had $31 billion in outstanding 401(k) loans, a fivefold increase from $6 billion in 1989. Between 1998 and 2004, an average of 12% of families with 401(k) plans borrowed from them. "They don't necessarily pay penalties. But the penalty is that they have fewer retirement savings," said Christian Weller, an author of the study.