The root of the Great Financial Crisis of 2008-2009 lay in poor-quality residential mortgage loans made by financial institutions. A set of academic research papers established that lenders made poorer quality loans when they anticipated selling the loans to investors rather than continuing to own the loans until they matured. When loans were sold, a complex securitization process led to a large distance between the originator of a mortgage and the final investor in the loans. Amit Seru, PhD '07, and co-authors established in an important series of papers that focused on 1) keeping most characteristics of loans the same, loans that were only marginally easier to securitize had significantly higher default rates than those that were marginally more difficult to securitize, 2) (in work with Professor Uday Rajan) securitized loans, the interest rate (which represents the compensation to investors for bearing the risk of default by the borrower) became an increasingly worse predictor of default in the build-up to the GFC, and 3) information passed on to investors by mortgage securitizers was limited and sometimes outright fraudulent. In another crucial strand of work, Professor Amiyatosh Purnanandam demonstrated that 1) loans held by banks on their own balance sheets had lower default rates than otherwise identical loans sold by banks to investors and 2) (in work with Taylor Begley, PhD '14, and Kuncheng Zheng, PhD '15) even with securitized loans, default rates were lower when the riskiest tranche was held by the lender rather than sold to investors. Collectively, the work done by Ross faculty and PhD alums showed that the ability to securitize mortgage loans undermined the incentives of lenders to the point that low-quality mortgage loans were made, essentially providing the dry timber that fueled the GFC.