The CDO-Squared (CDO²), takes the crown in my opinion as the most ridiculous yet impressive feat of advanced financial engineering. The banks took already complex, risky repackaged debt, sliced it into layers, and then repackaged those layers into an entirely new security. This created products so opaque, leveraged, and correlation-dependent that even the people selling them (and the rating agencies stamping them AAA) often didn’t fully understand the tail risks. When the 2008 crisis hit, these instruments helped turn a housing downturn into a global financial meltdown. CDO² were one of the building blocks to the great financial crisis. Bills and changes were made to prevent this from happening again. But I have a feeling more financial engineering will be made in the future. Comment below what will cause the next great financial crisis.(Seth)