Chains of CDS transactions can arise from a practice known as "netting". Here, company B may buy a CDS from company A with a certain annual "premium", say 2%. If the condition of the reference company worsens, the risk premium rises, so company B can sell a CDS to company C with a premium of say, 5%, and pocket the 3% difference. However, if the reference company defaults, company B might not have the assets on hand to make good on the contract. It depends on its contract with company A to provide a large payout, which it then passes along to company C.