CDOs, or collateralized debt obligations, were a major contributor to the 2008 financial crises. Developed and sold by investment banks, these products packaged millions of at-risk home mortgages into tradable securities that were sold to hedge funds, other banks, and pension plans. When this market collapsed, it brought much of the US equities market with it. Today, the market for CDOs is just a fraction of what it was in 2008, but a similar product - the CLO - is seeing record levels of investment. This article from the New York Times explores the state of the CLO market and why caution is needed. History doesn't always repeat itself, but this is something we will be following very closely in the months and years to come.