This document summarizes a student paper that analyzes the causes of adverse performance in collateralized debt obligations (CDOs) backed by asset-backed securities (ABS CDOs). Using data from 735 ABS CDOs, the paper finds: 1) CDOs with exposure to subprime and Alt-A mortgages from 2006-2007 significantly underperformed, 2) The identity of the CDO underwriter was a predictor of performance, with some banks having higher quality underwriting, 3) Original credit ratings assigned to CDOs failed to capture the true risks and were inflated. Overall, the collapse of the CDO market was caused by poorly constructed CDOs, irresponsible underwriting, and flawed