are more likely to give rise to patent portfolio races. We also discuss the welfare implications of these results. …Licensing in a patent thicket allows firms to either avoid or resolve hold-up. Firms' R&D incentives depend on whether … they license ex ante or ex post. We develop a model of a patent portfolio race, which allows for endogenous R&D efforts, to …

. This gives rise to a complements and a double mark-up problem. We compare the welfare effects of two different business … discourages entry and reduces innovation incentives, while horizontal integration always benefits from entry and innovation …