The paper explores the role and impact of information systems and infrastructures on financial innovation. More specifically it discusses the case of mortgage securitization as it is performed in the context of Master Trusts, a ready-made legal and financial innovation that enables originators to issue securities and sell them to investors. Empirical evidence from a case study on a large European securitizer shows that the information systems of the organisation that sponsors the Master Trust play a decisive role, not by simply performing calculations and risk assessment, but also by constantly re-affirming the Trust’s authority as a transparent infrastructure for mortgage securitization issuance. Future research directions are drawn towards further exploring the relation between techno-organizational and legal innovations in financial markets.