The MBS and CDS markets grew sharply in 2004?2007. The CDS market was $6.4 trillion in 2004 and grew to $57.9 trillion in 2007.However, the protection had one flaw: there still was a counterparty risk.A counterparty risk is the risk that a firm that is part of the hedge defaults. Thus, one can set up a perfect hedge against default risk of the MBS, but if one firm that sold you the CDS defaults then your investment is suddenly unhedged. Once your portfolio is unhedged, your chance of default increases. Thus, one firm defaulting can have a spreading effect across financial institutions and individuals across the globe. In general, this systemic risk seems to have been unanticipated by the financial market.