Wall Street crisis: Is this the death knell for derivatives? On page 62 of last year's accounts, under the heading "off balance sheet arrangements" Lehman had derivative contracts with a face value of $738bn Nils Pratley guardian.co.uk, Monday September 15 2008 09:18 BST If this is the death of Wall Street as we know it, the tombstone will read: killed by complexity. Derivatives in their baffling modern forms – collateralised debt obligations, credit default swaps and so on – lie at the heart of the failure of Lehman, Bear Stearns, Fannie and Freddie, and even our own Northern Rock. The...