Food for thought if you have any interest in the potential impact of the European situation on US banks.  I have no opinion yet on the quantitative significance of this.  $518 billion, though, is not prima facie chump change.

At Bloomberg, a report by Yalman Onaran: Selling More CDS on Europe Debt Raises Risk for U.S. Banks. 

The best bit: "The banks say their net positions are smaller because they purchase swaps to offset ones they’re selling to other companies."