2008 was not an ordinary year in the financial world, it witnessed the occurrence of one of the toughest crisis throughout the all history and this crisis is publicly known as the financial crisis 2008-2009. This research paper tests whether the credit derivatives are one of the main reasons for such crisis or not. Studying the causes and effects on the case of Lehman Brothers bank -the 4th largest investment bank in US in 2007- and how it was affected by such event. The case study provides an analytical analysis to test the bank's stand before and during the crisis, and its exact status on the period it declared bankruptcy in.