We present a model of information aggregation in which agents' information is represented through partitions over states of the world. We discuss three axioms, meet separability, upper unanimity, and non-imposition, and show that these three axioms characterize the class of oligarchic rules,...

We study markets for sensitive personal information. An agent wants to communicate with another party but any revealed information can be intercepted and sold to a third party whose reaction harms the agent. The market for information induces an adverse sorting effect, allocating the information...