Nonbanks and Mortgage Securitization

This article reviews the dramatic growth of nonbank mortgage lending after the Global Financial Crisis, especially to borrowers with lower credit scores, and the related importance of mortgage-backed securitization. Our literature review suggests that the existing theoretical and empirical work on securitization is more relevant to bank than to nonbank lenders, thus leaving outstanding questions as to why nonbank market shares have increased to their current levels and how best to structure nonbank oversight. To highlight key differences in the mortgage-lending incentives of banks and nonbanks, we build a simple theoretical model of bank versus nonbank mortgage lending and use it to generate and test empirical hypotheses. We find, in particular, that loans issued by nonbanks are more likely to prepay early than loans issued by banks, the difference not explainable by nonbank borrowers prepaying more rationally. Using regulatory filings from nonbanks that are typically unavailable to academic researchers, we examine the balance sheets and liquidity and capital positions of large Ginnie Mae nonbank servicers, which face and pose more risk in the current mortgage system. We find that on average these servicers have reasonable liquidity and capital positions relative to standard regulatory thresholds, particularly in 2022:Q1 after a few quarters of elevated profits. However, some large Ginnie Mae servicers appear to have inadequate capital, as gauged by risk-based capital measures. If defaults rise on a large scale, the liquidity and capital positions of these servicers may amplify the disruption in the mortgage and housing markets. Expected final online publication date for the Annual Review of Financial Economics, Volume 13 is November 2022. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.