We're at university together http://fittor.fun/collega-sxa/ xxxfollhd  But what if you have 70,000 trades on with Lehman, as JPMorgan did? Some are long, some are short, and a lot of them partially offset each other. One day you buy one CDX index, the next day you sell a different CDX index. Two separate trades, two separate contracts, but for economic and risk management purposes very close to offsetting.