We provide novel evidence of misaligned incentives fueling a portion of the 2000s mortgage boom. We document that private mortgage insurance (PMI) companies expanded insurance issuance on high-risk mortgages purchased by Fannie Mae and Freddie Mac at the tail end of the housing boom, without changing pricing and despite knowledge of heightened housing risk. The expansion of PMI facilitated an unprecedented increase in Fannie and Freddie’s risky purchases, extending the mortgage boom into 2007 and precipitating their collapse. We argue that this unraveling reflects a general moral hazard problem in insurance, coupled with misaligned incentives in the government-backed mortgage market.

Credit record panel data from 1999–2010 indicates that the likelihood of home equity extraction (borrowing, on average, about $40,000 against one's home) peaked in 2003 when mortgage rates reached historic lows. We estimate a 27 percent rise in extraction in response to a 100 basis point rate decline, and that house price growth amplifies this relationship. Differential responses to interest rates and home price appreciation by borrower age and credit score provide new evidence of financial frictions. Finally, equity extractions are associated with higher default risk, consistent with the use of borrowed funds for consumption or illiquid investment.

From 2007 to 2009 U.S. house prices plunged and mortgage defaults surged. While ostensibly consistent with widespread “ruthless default,” analysis of detailed mortgage and house price data indicates that borrowers do not walk away until they are deeply underwater—far deeper than traditional models predict. The evidence suggests that lender recourse is not the major driver of this result. We argue that emotional and behavioral factors play an important role in decisions to continue paying. Borrower reluctance to walk away implies that the moral hazard cost of default as a form of social insurance may be lower than suspected.