Computational complexity and information asymmetry in financial products

This paper introduces notions from computational complexity into the study of financial derivatives. Traditional economics argues that derivatives, like CDOs and CDSs, ameliorate the negative costs imposed due to asymmetric information between buyers and sellers. This is because securitization via these derivatives allows the informed party to find buyers for the information-insensitive part of the cash flow stream of an asset (e.g., a mortgage) and retain the remainder. In this paper we show that this viewpoint may need to be revised once computational complexity is brought into the picture. Assuming reasonable complexity-theoretic conjectures, we show that derivatives can actually amplify the costs of asymmetric information instead of reducing them. We prove our results both in the worst-case setting, as well as the more realistic average case setting. In the latter case, to argue that our constructions result in derivatives that “look like” real-life derivatives, we use the notion of computational indistinguishability a la cryptography.