Example of contract network among three banks. Each bank balance sheet consists of assets and liabilities. The assets of one bank are liabilities of another bank. (Top) Credit contracts are represented as arrows (pale red) from the lender to the borrower. Pale blue arrows represent investment in assets issued by entities external to the banking system. (Bottom) Derivative contracts are represented as orange arrows from the seller to the buyer, while the reference entity is indicated by the violet dashed arrow.
Battiston, S., Caldarelli, G., May, R., Roukny, T., & Stiglitz, J. E. (2015). The Price of Complexity in Financial Networks. Available at SSRN 2594028.