Motivated by the structure of existing pollution permit markets, we study the equilibrium path that results from allocating an initial stock of storable permits to an agent, or a group of agents, in a position to exercise market power. A large seller of permits exercises market power no differently than a large supplier of an exhaustible resource. However, whenever the large agent’s endowment falls short of its efficient endowment —allocation profile that would exactly cover its emissions along the perfectly competitive path — market power is greatly mitigated by a commitment problem, much like in a durable-good monopoly. We illustrate our theory with two applications: the U.S. sulfur market and the global carbon market that may eventually develop beyond the Kyoto Protocol
