JP Morgan recently announced a $2 billion loss, which renewed criticisms that originally surfaced during the credit crisis. While final details are still to come, initial reports suggest that much of the loss is attributable to the sale of Credit Default Swap (CDS) contracts. Similar exposures helped lead to the downfall of Lehman Bros., Bear Sterns, and AIG following the Crash of 2008. (See the article here, Fox Business.)
Dolvin, Steven D., "CDS Trades Continue" (2012). All Chapters. 8.