Systemic financial risk is one of the most significant collective action problems facing societies. The Great Recession brought attention to a tragedy of the commons in capital markets, in which market participants, from the first‐time homebuyer to Wall Street financiers, acted in ways beneficial to themselves individually, but which together caused substantial collective harm. Two kinds of risk are at play in complex chains of transactions in financial markets: ordinary market risk and systemic risk. Two moral questions are relevant in such cases. First, from the standpoint of interactional morality, does a person have a moral duty to avoid risk of harm to others if their financial transactions contribute in some way, however small, to the loss or harm? This article identifies the conditions in which persons are morally responsible in such cases. Second, from the standpoint of institutional morality, how should society distribute the risk of harm associated with massively complex financial markets? This question is considered in the context of the home mortgage credit market. Luck egalitarianism, in particular a Dworkinian insurance scheme to allocate risks and resources relating to mortgage credit and private home ownership, offers substantial promise.