This article examines the legal structure of complex structured finance transactions – notably collateralised debt obligation (CDO) – and explores in particular the regime of legal duties and liabilities designed to protect investors. The article critically assesses whether the existing law is adequate to hold to account the main actors involved in these transactions, namely SPV directors, trustees and asset managers. It also explores more specific avenues to establish accountability, namely the law of misrepresentation and fiduciary law. The analysis shows that in the context of structured transactions there remains an accountability problem due to the limited extent of the applicable duties, the nature of the conflicts of interest, the problematic disclosure (misrepresentation) of the transactions’ risks. The article contends that the complexity of the legal relationships underpinning CDOs and the resulting asymmetry of information between financial institutions on the one hand and investors on the other pushes for either a broader application of fiduciary obligations or alternatively a statutory redefinition of structured transactions.