One of the acknowledged benefits of patent clearinghouses is that they favor the diffusion of technology. In traditional clearinghouses, patents are usually sold at a pre-set price, bundled in patent pools. Recently, a new form of clearinghouse in the biotech industry has been observed, where patent prices are instead bargained over by the clearinghouse members. Exchange is then guaranteed by arbitration agreements to which the negotiating parties are bound, should their bargaining reach a dead end. This paper assesses the effect on technology diffusion of this new type of patent clearinghouse. We show such arbitration agreements, through their effect on the outside options, may reduce the incentives of a member of the clearinghouse to license to non-members. This entails that the clearinghouse may actually restrict the diffusion of technology.