I think contagion risk could also be a factor. Take BP for example. If upstream and downstream were separate companies then the Texas City accident wouldn't have affected the share price of the E&P business, and the GoM accident wouldn't have affected the value of refining.
CDS had no financial backing other than the name and reputation of the company issuing them.
No, a CDS contract usually requires collateral to be deposited equal to the change in the value of the contract. This way the reputation of the issuer is irrelevant. This was the downfall of AIG as they didn't account for all the collateral they had to post when lehman & other banks went south. P.s. In the case of CDO's the problem was working out the current value of the contract, nothing to do with collateral.
pdf if you are masochistic
What is bad about PDFs? Does it not display them well? I have lots of documents in PDF that I would like to read on a Kindle.